The ultimate Drupal to WordPress migration checklist

Migrating websites to a different content management system platform is incredibly complex but developers and site owners often underestimate the amount of work involved. Drupal to WordPress migrations can be especially tricky because they target very different types of users. You can quickly run into trouble if you start a migration project without considering some key areas.

My own migration project framework starts off with an analysis phase designed to discover as much as possible about the client’s needs and the impact on project resources. Over the years I’ve compiled a set of questions and considerations specifically for Drupal to WordPress migrations.

Developers and site owners can use this list to better understand their project’s scope. I’ve rather cheekily referred to it as The ultimate Drupal to WordPress migration checklist but in reality, it’s more of a working document that’s continually refined. The checklist is currently organised into three main areas that often concern my clients: understanding their migration requirements, auditing the existing Drupal site and addressing any SEO impact of the migration.

Migration requirements

These migration requirements will help you estimate a budget for your project.

  • List the Drupal content types to export as WordPress pages
  • List the Drupal content types to export as WordPress posts
  • List the Drupal content types to export as WordPress custom content types
  • Will custom content type development be needed?
  • List the content types that will be merged (if any)
  • Do you plan to re-organize your categories and tags?
  • List of terms to export as WordPress categories (remaining will be exported as tags)
  • Do you want to migrate comments?
  • Do you want to migrate Drupal users?
  • What will be your WordPress default category?
  • How do you want to handle the Drupal legacy file directory?
  • Are there any content sources outside of the Drupal database? (For example, static HTML files or external databases.)
  • What will be your WordPress permalink structure?
  • How do you plan to handle URL redirects?
  • Do you expect any data cleaning to be necessary?
  • Do you want me to install and configure WordPress on your server?
  • Do you want me to import the migrated database to your live server?
  • If any problems occur with your hosting provider during the migration, do you need me to troubleshoot?
  • Will you be redesigning your site or do you plan to convert your existing Drupal theme to WordPress?
  • If you plan to redesign your site, will you be using a ready-made theme or custom theme?
  • Who will be responsible for developing and configuring your WordPress theme?
  • Do you need to merge multiple domains or sub-domains into a single WordPress installation?
  • Do you need to merge content and configuration from an existing WordPress installation? (This may be necessary if you have already started developing the WordPress site prior to content migration.)
  • Is there an e-commerce component to the migration?
  • What are your SEO requirements? (We may need to complete the separate SEO To Do list.)

Drupal content audit

Understanding as much as possible about your Drupal installation will help you come up with a more precise estimate for your migration project. The content audit may take some time to complete but the process will give you a better idea of how much work will be needed to migrate your site.

  • Have you created a site map of your Drupal site?
  • What is the approximate number of Drupal nodes to migrate into WordPress. The number of Drupal nodes does not usually play a big factor in the complexity of the migration. However, it will still be useful to get an idea of the number since many nodes can have an impact on how long it takes to troubleshoot migration problems.
  • Please list the Drupal content types to migrate into WordPress. Additional migration MySQL queries will be needed for each Drupal custom content type. WordPress supports page and post content types as standard. Additional development work will be needed to support other content types.
  • Please list your Drupal custom fields. As with custom content types, custom fields in your Drupal installation will need additional work to support them under WordPress. We will need to specify how the field content is stored in WordPress, for example, by setting post meta key strings or custom tables.
  • Please list your Drupal modules and site functionality. Can the functionality can be handled with existing WordPress plugins? Will you need to develop custom plugins?
    Do you have blocks, views and panes with important content? Many Drupal sites display content in this way. Your SEO may be affected if you receive lots of traffic to pages with blocks, views and panes.
  • Have you installed Drupal modules that generate metatag information contributing to your SEO?
  • Do you have on-page optimization coded within the Drupal theme templates that we need to preserve? This will be important for SEO. Usually, on-page optimization embedded into the content body will be preserved during a migration.
  • Please briefly describe what to do with multiple aliases. Drupal supports multiple URL aliases for nodes. These will need to be resolved when migrating to WordPress. How we approach this will have an impact on your SEO.
  • Are there URL structures in Drupal that you need to preserve for SEO?
  • Are any Drupal taxonomies particularly important? Some sites have taxonomy listings that attract valuable traffic so this may be important for SEO. Note that unlike Drupal which allows for multiple vocabularies, WordPress only offers one set of categories and tags out of the box. Replicating your Drupal taxonomy listings in WordPress may need additional development.
  • Please briefly describe what to do with duplicate terms. Duplicate Drupal terms can cause problems during a migration.
  • Please briefly describe what to do with problem terms. For example, WordPress has a 200 character limit for terms. Any Drupal terms longer than 200 characters will need to be truncated. This may impact SEO if you receive lots of traffic from term indexes.
  • How many users do you have? The number of users doesn’t play a big factor during a migration but it may be useful to know. On some sites, users have associated pages that may be important for SEO.
  • Please list and brief description of user roles. Your Drupal user roles may need to be converted into WordPress roles.

SEO

These are tasks for projects where SEO is a major consideration. If SEO is critical to your site, you should hire your own dedicated SEO consultant.

  • Perform a pre-migration SEO audit
  • How will changes to menu navigation affect SEO?
  • How will changes to breadcrumb navigation affect SEO?
  • How will changes to site hierarchy affect SEO?
  • Crawl Drupal site to build database of URLs
  • Crawl WordPress site and compare counts with results from Drupal
  • Build database of authoritative content URLs and ensure these remain accessible after migration (e.g. via redirect if necessary)
  • Ensure changes to WordPress theme template will not adversely affect authoritative content
  • Identify how dynamically generated and statically set URLs will change (for example Drupal node IDs vs WordPress post IDs; Drupal URL aliases vs WordPress permalinks/post names)
  • Build list of changed URLs for redirection
  • Review title and meta description tags
  • Migrate title and meta description tags to SEO plugin e.g. Yoast
  • Identify top keywords and how they will be implemented in WordPress (e.g. do we manually set Yoast focus keyword for posts?)
  • Add Open Graph social meta data (for example via Yoast plugin)
  • Ensure theme is responsive for ‘mobile-friendliness’
  • Install redirection plugin (or implement via htaccess)
  • Install XML sitemap WordPress plugin
  • Install schema markup (rich snippet) WordPress plugin
  • Review WordPress robots.txt file
  • Check legacy Drupal site links to ensure WordPress redirects work correctly
  • Assess how page speed will affect SEO (anecdotal evidence says that page speed improves after a move to WordPress but verification is necessary)
  • Ensure live WordPress site is not set to noindex
  • Ensure correct timezone is set in WordPress
  • Perform a post-migration SEO audit

Why is Drupal the second most dreaded platform?

According to the Drupal Shell site, Drupal is the second most hated CMS platform. I think this sounds a little harsh and digging into the source on stackoverflow, we find that it’s actually listed as the second most dreaded platform. While perhaps more even-handed, I’m still not at all surprised as a large chunk of my business is made up of people migrating from Drupal to WordPress. To be fair, WordPress fans don’t have much to cheer. Their platform of choice appears as number three of the Content Management Platforms (CMS) listed. Still, Drupal had (has!) such a loyal following so why does it draw out such a reaction from respondents?

The dreaded Drupal can of worms

First-mover advantage

Let’s take a quick look at the history of the major CMS platforms currently in use. Drupal was, in the first decade of the 2000s, arguably the top CMS for building websites. It had first-mover advantage, having launched as an open source project in 2001—years before its contemporary competitors. Drupal 4 was released in mid-2002 and started appearing on most developers’ radar by around 2004–2005. Its only real competitor was Movable Type which offered simple blogging capability. WordPress was at version 1 in 2004 and was then also more of a blogging tool. Magento and Joomla would come around quite a few years later, launching in 2007 and 2009 respectively.

CMS version 1 release timeline
2001 Drupal
Movable Type
2004 WordPress
2007 Magento
2009 Joomla

I remember my first foray into Drupal development in 2003. A freelancer colleague kept raving about how great it was and that I should give it a try. (Incidentally, he subsequently became very active in the Drupal community and ended up having his theme bundled in with core.) At that time, I’d been hand-coding websites and building custom ‘site generators’. CMS platforms hadn’t taken off so people were coming up with their own solutions from managing site content. For example, I worked with a top-tier mobile operator in the early 2000s who asked me to build a web-based knowledge management that stored content in Microsoft Access and published static HTML on their intranet using VBA.

When Drupal came along, it captured the entire range of the market. Hobby sites, small businesses, small and large charities, multi-nationals all adopted Drupal because its flexibility.

Features for free

Eventually, my colleague’s insistence overcame my resistance to learning new technology. As you can imagine, Drupal, in comparison to hand-coding from scratch, was an absolute dream. I could now build feature-rich websites with login functionality, CRUD and custom layouts in maybe one-fifth of the time and cost. Like my colleague, I started raving about Drupal and began recommending it to clients and colleagues.

Drupal was without any doubt the most powerful website development platform available. Nothing else in the open-source market could touch it. It was also fun building websites with Drupal. You could get instant gratification by installing and playing with the many available modules. Every developer facing a deadline and budget loves features for free when the alternative is hours of coding and debugging. Features for Free is great…unless you have to maintain all those features. More on this later.

Similarly, site owners—who often don’t care that much about the technology—loved that their developer could deliver a widgety-thingamajig-feature at a reasonable price. They’d request some functionality and the developer would say, “Yeah, we can do that with Views.” “Yeah, there’s a module for that, no problem.” “Oh, no module for that but we can build one without a huge site overhaul.” It was great until, well…

The Drupal can of worms

Well, fast-forward to 2018 and nearly every Drupal site I encounter is a huge can of worms. Those great Features for Free aren’t so great when the modules have been abandoned. They’re not great when, years after installation, no-one remembers which module controls what and how everything ties together. Sure, documentation and well-commented source code commits are best practice. Perhaps enterprises can afford to maintain a stable of diligent developers. But many sites are cobbled together on a legacy of little to no budget and a revolving door of budget developers with varying skills.

Over time, each person adds their own hacks and disappears. No-one willingly runs updates and upgrades because who enjoys having a nervous breakdown? Run an update and risk a WSOD. Spend hours tracking down some obscure, unsupported and misbehaving module that’s absolutely crucial to the way this particular site works…for free? No thanks!

Fully-documented sites and well-specified upgrades are what everyone in the industry aims for. However, real-life tends to go something like this:

Site owner: Hey, remember that site you built for me a couple of years ago? I’d like to…
Developer: mumble…mumble…upgrade to Drupal 5…mumble…price….
Site owner: Hmmm, I’m good for now…kthxsbye…

A couple of years later…

Site owner: Hey, this guy built a site for me. I’d like to…
Developer: mumble…mumble…upgrade to Drupal 6…mumble…price….
Site owner: Price???!!! kthxsbye…

A couple of years later…

Site owner: Hey, I have this site…
Developer: Erm…Drupal 7…rebuild the site…
Site owner: What???!!! kthxsbye…

A couple of years later…

Developer: Oh, how many thousands of monies did you say is burning a hole in your pocket? Because, you know, Drupal 8…

Upgrades and backward compatibility

Of course, poorly documented, buggy and abandoned add-ons are all too common in the WordPress world. The big difference is backward compatibility. WordPress has been great with ensuring problem-free updates: you see core, plugin or theme updates available; you click Update Now; a few seconds (or minutes at most) later you’re done. You can move on with your day and not give it another thought.

In contrast, updating Drupal can ruin your day. (Or night if you’re scheduling the work during off-peak hours.) Drupal updates can go horribly wrong. During the pre-Drupal 8 days, it wasn’t out of the ordinary to spend hours of site rebuilding after one of the module updates took down the site. Which module? Well, you’d have some trial-and-error testing a series of modules one-by-one until you find the culprit. Updating Drupal is often a dreadful experience.

Sensible developers test updates on a development server first, then get the site owner to test on staging before rolling out to live. This is best-practice. Everyone should be following this workflow regardless of the platform. Yes, if there’s money for it. This effort comes at a price and many, if not the majority, of smaller businesses, not-for-profits and hobby sites just don’t have the cash. People have found that WordPress lets them cheat the recommended workflow. If they see updates they just go ahead and do it live because there are rarely any problems.

Core upgrades for major Drupal versions are another level of pain for the site owner. Drupal 6, 7 and 8 are all so different in architecture from previous releases that upgrading essentially means re-building the site from scratch. This is too much to expect for many. No wonder site owners would rather hobble along with their outdated duct-taped CMS.

The dread

Keeping Drupal up-to-date is expensive for the owner and time-consuming for the developer. Site owners dread to think about the fees. Maintainers dread jumping through hoops just to run simple module updates. Newly hired developers dread what they might find when they peek under the hood.

I started Another Cup of Coffee as a Drupal development shop because it allowed us to offer powerful functionality at a reasonable price. Years later, although I’m no longer in the business of building Drupal sites, I do remember the feeling of dread when time came to tinker with a mature installation. I have every sympathy for those who list Drupal as their second most dreaded platform. It seems that everyone feels The Drupal Dread, unless of course, they make lots of money from support.

Photo by Bill Craighead on Unsplash

How to fix ‘Error Code: 2013 Lost connection to MySQL server during query’

Content migrations usually involve running complex MySQL queries that take a long time to complete. I’ve found the WordPress wp_postmeta table especially troublesome because a site with tens of thousands of posts can easily have several hundred thousand postmeta entries.

If your query ends up taking more than a few minutes to complete, you may encounter the following error:

Error Code: 2013. Lost connection to MySQL server during query

This happens because the connection between your MySQL client and database server times out. Essentially, it took too long for the query to return data so the connection gets dropped. The MySQL documentation suggests increasing the net_read_timeout or connect_timeout values on the server. If this doesn’t solve the problem, you may need to increase your MySQL client’s timeout values.

MySQL Workbench

You can edit the SQL Editor preferences in MySQL Workbench:

  1. In the application menu, select Edit > Preferences > SQL Editor.
  2. Look for the MySQL Session section and increase the DBMS connection read time out value.
  3. Save the settings, quite MySQL Workbench and reopen the connection.

Navicat

How to edit Navicat preferences:

  1. Control-click on a connection item and select Connection Properties > Edit Connection.
  2. Select the Advanced tab and increase the Socket Timeout value.

Command line

On the command line, use the connect_timeout variable.

Python script

If you’re running a query from a Python script, use the connection argument:
con.query('SET GLOBAL connect_timeout=6000')

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Post-migration troubleshooting: Gateway timeout when enabling plugins

Here’s one that caught me out on a recent Drupal to WordPress migration. As is common with my projects, there were three parties involved: the client, an external development team and myself. The WordPress site was first built on the development team’s server, after which it was migrated to my local environment. When everything was ready for beta testing, we moved the site over to the client’s staging server on a newly activated account over at Kinsta. Eventually, we’d move it over to a live server, also hosted on Kinsta.

Diagram of Drupal to WordPress migration workflow for this project

After some initial tests on staging, I found that deactivating and reactivating plugins would cause the site to hang and show a ‘504 Gateway Time-out’ error. This happened when re-enabling some but not all plugins.

I initially suspected some misconfiguration at the hosting end because there were some hitches with the newly create account. At the outset, the account’s server had an issue which Kinsta support needed to fix. For convenience, we’d also made use of Kinsta’s free site migration service. This is where they’ll migrate an existing WordPress site into their environment. Though it would have been easy enough for me to do, we thought to give it a try. In hindsight, this was a bit of a mistake. The site migration service itself was fine but it did end up causing some confusion. First, a miscommunication in the migration request caused them to create a temporary domain we didn’t want. They helpfully solved this by giving us a second temporary domain. However, they’d also upgraded everything to PHP 7 in the process. All of these issues were possible suspects for the time-out error but turned out to be red-herrings.

It took some time to pinpoint the cause behind the Gateway Time-out error. I do have to say that Kinsta support were very responsive throughout the troubleshooting process. They eventually put a senior engineer on the case who found the problem. It turned out the problem wasn’t to do with Kinsta at all. There was a leftover setting from the original development team’s server server. It was a valid format so didn’t cause an issue on either my local server or my staging server. However, it apparently can cause issues with plugins and did on the Kinsta environment.

What was the setting? The WordPress upload path directory was set to the development team’s server path e.g. /home/dev/public_html/sitename. Throughout the migration, I’d been doing a database search-and-replace looking for their development domain. Somehow, as the site moved from different servers, that server path string remained in the database, only to cause a problem when the site landed in the destination server on Kinsta.

I’m not sure if there would have been any way to have caught this problem earlier. It’s one of those obscure errors that are easy to overlook and take time to resolve. There’s also no practical way to do a database search-and-replace for every imaginable string. I’ll have to rack this one up to experience.

How to change the WordPress table prefix prior to a migration

When working on a Drupal to WordPress migration project, I like to migrate into a set of intermediary WordPress tables that live in the Drupal database. These are working tables where I can run various scripts to process and clean up the content before exporting to a working WordPress installation. It’s not necessary to do this but I find it convenient to run scripts on the same database rather than deal with two separate database connections.

Note that some people suggest renaming the table prefixes to improve security. My use of the table prefixes is simply to create temporary containers for the migration. While non-standard prefixes might help prevent ‘script kiddie’ attacks, I find it isn’t worth the disadvantages that come with this sort of security through obscurity (or more precisely, security through minority) approach. Here are two articles give a deeper explanation of topic:

SQL queries to change the WordPress table prefixes

You can start with a freshly installed WordPress database. Dumping this and importing to your Drupal migration database will give you all the tables with the correct WordPress schema. I use the acc_ prefix but you can use whatever you want.

Rename the tables with these queries:

RENAME table `wp_commentmeta` TO `acc_commentmeta`;
RENAME table `wp_comments` TO `acc_comments`;
RENAME table `wp_links` TO `acc_links`;
RENAME table `wp_options` TO `acc_options`;
RENAME table `wp_postmeta` TO `acc_postmeta`;
RENAME table `wp_posts` TO `acc_posts`;
RENAME table `wp_terms` TO `acc_terms`;
RENAME table `wp_termmeta` TO `acc_termmeta`;
RENAME table `wp_term_relationships` TO `acc_term_relationships`;
RENAME table `wp_term_taxonomy` TO `acc_term_taxonomy`;
RENAME table `wp_usermeta` TO `acc_usermeta`;
RENAME table `wp_users` TO `acc_users`;

Testing the migration results

If you need to point a WordPress installation to these tables for testing, you’ll need to do two things:

  1. Update the $table_prefix setting in the wp-options.php file
  2. Update the options and usermeta tables

Updating the $table_prefix setting in the wp-options.php file is straightforward. Open the file and edit the line:

$table_prefix  = 'acc_';

In WordPress, prefixes are saved as entries in the options and usermeta table. Check for entries containing the prefix:

SELECT * FROM `acc_options` WHERE `option_name` LIKE '%wp_%';
SELECT * FROM `acc_usermeta` WHERE `meta_key` LIKE '%wp_%';

When you have all the entries, update them with the new prefix. The query will probably look something like this:

UPDATE `acc_options` SET `option_name` = 'acc_user_roles' WHERE `option_name` = 'wp_user_roles';
UPDATE `acc_usermeta` SET `meta_key` = 'acc_capabilities' WHERE `meta_key` = 'wp_capabilities';
UPDATE `acc_usermeta` SET `meta_key` = 'acc_user_level' WHERE `meta_key` = 'wp_user_level';
UPDATE `acc_usermeta` SET `meta_key` = 'acc_user-settings-time' WHERE `meta_key` = 'wp_user-settings-time';
UPDATE `acc_usermeta` SET `meta_key` = 'acc_user-settings' WHERE `meta_key` = 'wp_user-settings';
UPDATE `acc_usermeta` SET `meta_key` = 'acc_dashboard_quick_press_last_post_id' WHERE `meta_key` = 'wp_dashboard_quick_press_last_post_id';

A word of warning: it’s easy to forget to change the prefixes back to match the final WordPress installation. If you do, the WordPress user accounts will have problems, such as the Dashboard controls not being visible after logging in. Because of this, I tend to have a separate testing installation that gets an import of the working tables.

Post-migration troubleshooting: WordPress redirects to old site after updating database

If you’ve ever migrated a WordPress site, either to another URL or for a Drupal to WordPress migration project, you’ll know that WordPress stores the domain name in its database. This means you’ll have to jump through some hoops when moving WordPress to another environment. A critical step is to update the database to reflect the new domain. My favourite tool for this used to be the database search and replace script from interconnect/it. The script is PHP-based so runs on all environments that host WordPress. I now prefer WP-CLI’s wp search-replace command when on my own development environment, or for client hosting that supports it. Nevertheless, interconnect/it’s tool is still my fall-back option for clients of my Drupal to WordPress migration service since many use hosts that don’t offer command-line access.

In nearly all cases, updating the siteurl and home fields in the wp_options database table achieves the bare minimum to get the site working after migration. Running a search-and-replace across the WordPress database (in particular, the wp_posts table) will resolve broken links containing absolute URLs.

wp-admin still redirects to the old site after updating wp_options?

Once-in-a-while, I’ll encounter a migration project where wp-admin still redirects to the old site even after running through the obvious steps of:

  1. updating the database;
  2. clearing the browser cache;
  3. clearing the server cache.

It happens very rarely so I have yet to discover the cause. I suspect it’s something to do with sites that had a caching plugin installed, such as W3 Total Cache.

If you ever find yourself in this situation, the best workaround is to add the following two constants in wp-config.php:

define('WP_HOME', 'http://' . $_SERVER['SERVER_NAME']);
define('WP_SITEURL', WP_HOME . '/');

This isn’t a nice long-term solution but it should at least enable you to log in for some basic site administration. Once you’re able to log in to the WordPress Dashboard, disable any caching plugins after first clearing their cache.

Handling the Drupal file directory when migrating to WordPress

Attaching media the WordPress Media Library are one of those things that many clients don’t realise can add lots of time to a Drupal to WordPress migration project. The reason is a little detailed and involves some knowledge of WordPress’ inner-workings.

When you upload a file to the WordPress Media Library, WordPress does some magic behind the scenes and creates different bits of metadata. If you upload, say, an image, it creates thumbnail versions of the image based on the settings in Settings > Media Settings > Image sizes. It also adds a bunch of serialized data in WordPress’ attachment table (wp_attachment_metadata). If you get this information wrong, displaying attachments will fail. For example, Featured Images in posts will not display because the theme has no reference for which thumbnail to display when a post is delivered.

Folders symbolising media migration from Drupal to WordPress

Because of the necessary metadata that needs to be generated, attaching media to the Media Library is therefore not feasible through a database migration using purely SQL queries. If you’d like media attached, a separate custom script is needed to pick up all your files under the Drupal file directory and attach them using different mechanisms, such as XML-RPC, WP-CLI or a custom plugin. It adds to the cost so many of my clients see this as a ‘nice-to-have’ rather than a necessity.

As an alternative, my clients and I have come up with different ways to handle the Drupal files and media items when migrating to WordPress:

  1. Leave the Drupal file directory path intact on the WordPress installation server. This is the easiest option which most clients take because it’s cheaper. No changes are needed to the post and page content because the already embedded path will still be valid. However, we may have to make changes to the WordPress theme so that it knows the path to legacy Drupal file path. Future uploaded files will be fine but legacy posts will point to the Drupal file paths. This is not nice and a bit of a hack but it’s a cheap and quick solution. Media items will not appear in the WordPress Media Library.
  2. Move the Drupal file tree to the WordPress wp-content directory. We then need to do a search-and-replace to amend the link path within the post content. There’s a small risk of broken links if we don’t get the search pattern right but generally it’s a straightforward process. Media items will not appear in the WordPress Media Library.
  3. Use a plugin or custom WordPress code to attach files from an external URL. The client’s developer normally handles this work in-house so I can’t offer much feedback on this method. It seems to work reasonably well.
  4. Manually upload all the files to the WordPress Media Library. This is of course the most tedious and time-consuming option. Nevertheless, those with smaller sites or have gone this route. If you’re trying to save on budget and have lots of time on your hands, you might want to consider it.
Graphic courtesy of and copyright morguefile.com user Ladyheart

How to write a Drupal to WordPress migration mapping document

Performing a Drupal to WordPress migration can be very complex, especially if you have many content types. You’ll make the process easier if you create a migration mapping document beforehand. A common migration mapping is to convert Drupal pages to the WordPress page type and Drupal stories to the WordPress post type. However, many Drupal sites also have custom content types so the mapping won’t always be obvious. Will they be converted to WordPress pages or posts? Do they have custom fields? How about views and panels? Perhaps you may need to develop a new WordPress content type to support them.

Your Drupal to WordPress migration mapping document will give everyone involved a clear idea about how the Drupal content will be migrated to its equivalent in WordPress. If you’re running the migration yourself on a simple blog or company site, there might not be much need to spend the extra effort but sometimes running through the process uncovers aspects of the site that you may have overlooked. I’d say this is vital for migrations where you’ve hired someone else or if you have a content-heavy or news-based site. Not only will the document make it easier for someone to quote for the job, you’ll also have a specification for reference when checking the results post-migration.

Creating the content mapping

Creating the mapping needn’t be complex. The easiest way is draw up a table with at least two columns. On the left column, list down all your Drupal content types. Next write down equivalent WordPress content type on the right column for each row of Drupal content types. You might find it helpful to have a third column for writing notes, such as whether or not you need do develop a new custom WordPress content type. If your Drupal content type has custom fields, simply add rows below each type listing the fields.

Sample content mapping table
Drupal WordPress Notes
Drupal WordPress Notes
Drupal WordPress Notes
  Field 1   Field 1 Notes
  Field 2   Field 2 Notes
  Field 3   Field 3 Notes
Drupal WordPress Notes
Drupal WordPress Notes
Drupal WordPress Notes

Developers responsible for the migration can also add additional sections specifying back-end table and field names where the relevant content can be found.

Creating the functionality mapping

Follow a similar procedure to create the functionality mapping. Instead of content type names, list down Drupal modules and equivalent WordPress plugins.

Preparing for your migration project

The migration mapping document will have helped prepare you for your project and provide you with a specification for the migration. You might also find the following articles useful:

A little plug to keep the lights running. If you think all of this work is too much trouble, please consider hiring me for your Drupal to WordPress migration project.

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Importing a WordPress database: How to fix the Unknown collation: ‘utf8mb4_unicode_ci’ error

If you do a lot of exporting and importing to different database servers, you’ll be familiar with the frustration of encountering MySQL import errors. Every so often when importing a WordPress dump file into a client’s database, I will encounter an Unknown collation error like the following:

Unknown collation: 'utf8mb4_unicode_ci'

Sometimes it will come up as:

Unknown collation: 'utf8mb4_unicode_520_ci'

This is caused by a difference in encoding types between the source and destination databases. It usually happens when you export from a newer MySQL database (MySQL 5.5.3 and above) which uses utf8mb4, then attempt to import into an older version using utf8. If you are importing from a dump file generated from a MySQL 5.6 database, you may get the utf8mb4_unicode_520_ci message. The 520 refers to MySQL’s use of Unicode Collation Algorithm 5.2.0. Unknown collation errors may also happen if you are trying to import a MariaDB database into MySQL. I tend to get unknown collation errors with my Rackspace Cloud accounts after Rackspace started offering MariaDB as a database option.

Ideally one would upgrade the older destination database but this isn’t always a realistic option. There are a number of discussion threads on the WordPress forum about what to do. Fortunately, many web hosting accounts have a phpMyAdmin interface which provides an easy work-around for the problem.

Format-specific options during a phpMyAdmin database export

  1. Log in to your database server using phpMyAdmin
  2. Make sure you select your database and go to the “Export” tab
  3. Select the “Custom” radio button
  4. Go the section “Format-specific options” and in the setting for “Database system or older MySQL server to maximize output compatibility with:” select MYSQL40.
  5. Scroll to the bottom and click GO.

phpMyAdmin format specific options to fix the Unknown collation: 'utf8mb4_unicode_ci' error

Other possible solutions include:

Since many of my WordPress database migrations are under my migration service, I don’t always have control over the client’s platform. The phpMyAdmin export format method is often the simplest solution.

Side-effects of a character encoding downgrade

You might be wondering about the purpose of encoding types and if there will be any side-effects of downgrading. Character encoding allows support for a set of characters, such as the Western alphabet, Asian scripts and non-alphanumeric symbols. Older utf8 databases support a smaller set of characters whereas utf8mb4 includes emojis, musical notation and Chinese Han characters. If you’ve ever exported a website from one CMS to another and found random characters scattered throughout the copy, it’s because of an incompatible character encoding.

Solving the unknown collation error as described here could mean you’ll end up with unsupported characters after your site migration. However, as with many of my Drupal to WordPress migration clients, in all likelihood you’ll be migrating from an older utf8 Drupal database to a newer utf8mb4-supported WordPress database. In this case, your old content will not have characters that will cause a problem after an encoding downgrade.

How to prepare for your Drupal to WordPress migration project

Any successful project requires careful planning and a Drupal to WordPress migration is no exception. It can be tempting to head straight to setting up WordPress, trying out new themes and experimenting with plugins. Website owners and administrators know their content is important but it can sometimes become an afterthought in the excitement to play with the new content management system. After all, you can use the Drupal site as the template and simply export over all the content over, right? For some site owners that’s all there is to it. However, you should be aware that site migrations can have hidden pitfalls that turn an apparently simple project into one fraught with complications.

The key to avoiding problems is to plan your Drupal to WordPress migration before you even touch your server. Whether you migrate the site yourself or hire me to help you, this guide will give you a head start with your planning. Keep in mind that general project planning principles apply but there are already many resources on this topic. I will focus on the areas important specifically for a migration from Drupal to WordPress.

Drupal to WordPress migration planning

Step 1: Consider why you are migrating to WordPress

There are many content management systems available and I’m going to assume you have already thought carefully about why you’ve chosen WordPress. For the sake of completeness, I’ll include this step because your reasons will determine whether or not the migration project will be a success.

In case you need a reminder about the merits of either CMS, here are a few Drupal vs WordPress posts:

If you haven’t already put together a migration requirements document, go ahead and create one now. I go through this migration requirements checklist with my own clients and it might help you too.

Step 2: Decide on your approach to building the WordPress theme

The WordPress theme, just like in Drupal, is what handles how your site looks. A migration to a new CMS often goes hand-in-hand with redesigning the site. I’ve put this step early on because a site redesign could be an entirely separate project. You might want to run in parallel with the migration or it could be something you’d want to start before kicking off the content migration.

You have three options:

  1. Redesign the WordPress site entirely.
  2. Create a custom theme based on your existing Drupal design.
  3. Use one of the many pre-made free or premium WordPress themes.

If you have a successful site, any change, whether it’s a redesign, restructure or move to another content management system should be carefully considered. This article at Search Engine Journal gives an excellent overview of the things you should keep in mind: How To Avoid SEO Disaster During a Website Redesign – Top Marketer Concerns

Step 3: Be aware of any SEO impact when migrating to WordPress

WordPress has an excellent reputation for being SEO-friendly but beware of taking this for granted. The Search Engine Journal post linked in step two should have given you a sobering outlook on how making changes to your site will affect your SEO. In my experience, preserving SEO takes a large part of the time and budget of many migration projects. Sometimes the cost will outweigh any benefit of trying to preserve the SEO customisations on your Drupal installation. This is often a commercial rather than technical decision. If you run a site that relies on search traffic, I recommend that you hire an SEO consultant to advise you. In fact, I will often work with and take direction from a client’s SEO consultant during a typical Drupal to WordPress migration project.

For more information about the kind of work involved, see Preserving SEO during a Drupal to WordPress migration. This SEO checklist will help get you thinking about any SEO impact the migration will have to your site.

Step 4: Gather as much information as you can about your Drupal installation

Knowing as much as possible about your Drupal installation will help me come up with a more precise estimate for your migration project. If you’re doing the migration in-house, it will help you plan how much time to set aside and which team-members need to be involved.

Site owners who built and manage the site will likely have records of some information but not necessarily all the details of how Drupal is configured. Site owners also come to me with a site built by a third-party. They have working knowledge on how to manage it and add content but not anything else. I can help you discover the information needed for the migration if you are in this position but you can save budget by doing some investigation yourself. Use my Drupal to WordPress migration worksheet as a guide.

The formal name for this is a site audit but essentially you need to find out about two areas:

  1. How to access your server
  2. What kind of content you have

Server audit

You’ll need your FTP server details to access your Drupal installation, media files and to upload the WordPress package. When running a migration, I like to download a full working version of the Drupal site on my local development server. This isn’t necessary but can be useful for figuring out formatting problems that crop after content migration. For example, you may find missing bits of text on WordPress and some investigation on the Drupal installation will show the text will be from a custom field or block.

The database server is necessary for exporting your Drupal database and setting up WordPress when the migration is complete. Some hosting providers offer access through a cPanel interface, a separate phpMyAdmin link or by command line. Gather all these details ahead of time will help get your project started quickly.

Content audit

The content audit helps you discover what type of Drupal content do you have. Drupal, like most other content management systems, keeps content in two places:

  • The database
  • On the server filesystem

Types of content include:

  • Nodes
  • Views
  • Blocks
  • Panes
  • Taxonomies
  • Static HTML files
  • Embedded media like videos, images and audio
  • File attachments
  • User profile information
  • Content metadata

You may be surprised where the different bits of content that make up your site ends up being stored. A content audit will avoid unnecessary complications with trying to hunt down bits of data mid-migration. My Drupal content audit checklist should get you started.

Step 5: Write a Drupal to WordPress migration mapping document

The migration mapping document will help both with quoting for project as well as keeping track of everything that needs to be done during the migration. It gives everyone involved a framework to work on.

I know, this sounds like a mouthful and so very tedious. Truth be told, few people find writing specification documents fun but it is a necessary step if you want to avoid unexpected costs and delays. The more detailed you are, the fewer surprises there will be for everyone during the actual migration. Your investigations during step 4 will lay the groundwork for the migration specification.

I will write another post on how to write migration mapping document but the document doesn’t have to very formal. All it needs to do is clearly convey the state of your Drupal site and what you’d like migrated to WordPress.

Ready for your migration project

Running through these steps will put you in a good position for your migration from Drupal to WordPress. Admittedly, there have been projects where I or the site owner didn’t bother to do any detailed planning and we were able to get by. Usually, this was because of limited budget or a rush to launch the new WordPress site. However, the projects where we took some time out to plan ahead were always closer to the estimated budget and posed fewer surprises.

A little plug to keep the lights running. If you think all of this work is too much trouble, please consider hiring me for your Drupal to WordPress migration project.

Drupal to WordPress migration service

Drupal 6 and Drupal 7 · All content · Custom content types · SEO · Plugins

If you’re not sure how to make the appropriate changes or would simply like someone else to do the work, please contact me and ask about my Drupal to WordPress migration service.

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Planning graphic courtesy of and copyright Free Range Stock, artist: Jack Moreh