Yoast SEO WordPress plugin version 19.7 was discovered to contain a conflict with other plugins which resulted in websites experiencing fatal errors.
This marks the third time this year that a conflict with another plugin caused a Yoast update to fail.
Fortunately, Yoast investigated the reports and swiftly published a new update that fixed the problem.
WordPress Fatal Error
There are multiple causes for a fatal error but in this situation it was caused by an update to Yoast SEO in which the coding conflicted with another plugin.
This can happen because two plugins are trying to do something but one is essentially cancelling out the other or otherwise preventing each other from functioning.
A metaphor for a plugin conflict could be two cars going in opposite directions on a single car road.
Ideally a plugin makes allowances in their coding for other plugins, especially common ones, so that neither plugin tries to do something that prevents other plugins from doing their thing.
This is exactly what happened with the Yoast 19.7 update.
Yoast 19.7 had a conflict with other plugins (or custom coding) that change the admin login URL.
Changing the login URL is a security measure designed to trick hacker software that automatically navigate to the default URL for adminstrator logins and attempt to guess the login password credentials.
Yoast Announces Update Bug
Yoast was 100% transparent about the bug and posted a tweet which described for users what was happening.
Yoast tweeted:
“After the release of Yoast SEO 19.7, we were informed that this version causes a fatal error when used in combination with plugins or code that alters the default WordPress login URL.
We’ve identified the problem and are working on a solution.”
One of the changes introduced with Yoast 19.7 (according to the Yoast plugin development changelog) was an improvement to how Yoast handles fatal errors by preventing it from running in the login page.
“Improves the handling of fatal errors in the front-end by preventing Yoast SEO to run in the login page, allowing users to access their dashboard.”
Could that have been the cause?
Why Do Fatal Errors Happen With Plugins?
Plugin conflicts are not exclusive to Yoast. It’s simply more noticeable when it happens to Yoast because their user base numbers in the millions.
However, this is the third time this year that a fatal error plugin conflict was associated with a Yoast plugin update this year.
Yoast SEO Plugin founder Joost De Valk explained in a tweet that it’s not always possible to account for the thousands of plugins in the WordPress ecosystem with which a coding conflict could happen.
He tweeted:
“This is the sort of #WordPress plugin conflict situation that I literally don’t know how to prevent from happening.
60,000+ plugins: how do you test your plugin against all of those.
If someone has good ideas, I’m all ears”
Joost also tweeted that Yoast always tests their plugin updates prior to release with many of the most popular plugins.
“We test against the big ones, not worried about those as much, but a couple small ones together still cause enough of a headache.”
“…it’s never fun when you break stuff. We test very rigorously and still stuff goes through. Building plugins for large amounts of users is “just” hard.”
Solution Offered Within Hours
Yoast published a new update within two hours of announcing that they identified a bug in the update and were working on a solution.
We’ve resolved the problem and released a patch. You can now safely update to Yoast SEO 19.7.1.
We’ve marked the incident report at https://t.co/sBvJewCAeX as resolved.
— Yoast (@yoast) September 20, 2022
What Action To Take
Yoast released a new update, version 19.7.1. The Yoast development changelog stated:
“Fixes a bug where a fatal error would be thrown in combination with certain plugins that change the standard login page URL.”
Users of Yoast SEO plugin may want to consider updating to the very latest version of Yoast, version 19.7.1