Community Central
Community Central

MediaWiki™ is the software which runs all of the wiki components on Fandom communities. Respecting our commitment to keep MediaWiki up to date on a regular basis after the implementation of the Unified Community Platform, we are running at least one major update every year. Those major updates are updating not only the MediaWiki version, also the extensions and functionalities used in the whole platform. The previous major update done in Fandom was the update to MediaWiki 1.37.

This upgrade won't change the design, so our wikis will keep the same look as they had previously. Our engineers will make the needed changes to be sure that our admins won't need to do design adjustments. Most of the changes will happen under the hood, meaning they're not user-facing, but they will be important to ensure that everything is still working correctly.

During the migration to 1.39, the wikis will be set in read-only mode. It shouldn't take more than 30 minutes (major wikis could need more hours). One week before migration, a banner will appear on communities to let them know the migration is scheduled. For one week after the migration, a similar banner to let users know the community is now on the new version.

If your wiki is experiencing problems after the migration, please contact to your Wiki Representative or Fandom Staff. There is also a specific channel in our Discord server created for conversations about the upgrade, go to #mediawiki-upgrade and feel free to ask your questions or concerns.

See more information about the upgrade process in this blog post.


In order to ensure a sweet upgrade, the migrations are done in different batches, starting with 3-4 wikis without complex extensions, and adding more traffic, content, and extensions progressively in the subsequent batches. Depending on the number of wikis and extensions included in every batch, it can take from 1 day to 2 weeks to complete.

  • December 2022: Upgrade preparation.
  • January 2023: Default Extensions Development.
  • February 2023: Community Team testing.
  • February 27, 2023: First batch is migrated.
  • March 2023: All the new wikis created in the platform will use MW 1.39.
  • March 2023: We start the migration of the top 5000 most visited wikis.
  • Mid March 2023: Wikis out of the top 5000 are starting to be migrated.
  • April 2023: Semantic MediaWiki and Cargo wikis are migrated.
  • May 2023: All the wikis are using 1.39.


The following list contains a summary of the most relevant changes for regular users and visitors. For a detailed list, see the official release notes.

Important notes for admins

  • CSS customizations should work as previously in 1.37. This upgrade hasn't introduced relevant changes in this area and our engineers have applied changes on their own to avoid moving this work to the admins.


  • SECURITY: HTMLUserTextField exposes existence of hidden users.
  • SECURITY: On action=rollback the message "alreadyrolled" can leak revision deleted user name.
  • SECURITY: ApiEditPage update title after redirects.

Articles and editing

  • Validate length of user email on Special:ChangeEmail/Special:CreateAccount.
  • Repair language selector for SVGs.
  • The auto-number headings feature was removed following a consultation due to performace reasons.
  • New deletetalk parameter on action=delete that allows you to delete the associated talk page of a subject page.
  • Similarly, new undeletetalk parameter on action=undelete that allows you to restore all revisions of the associated talk page.
  • The character > is included in the list of invalid username characters. It's a reserved delimiter for external user names.
  • Administrators now have the option to delete/undelete the associated Talk page when they are (un)deleting a given page. deletetalk and undeletetalk options were added to the delete and undelete actions APIs.
  • {{=}} is now a wikitext built-in magic word, expanding to =. This is conventionally used as an escape mechanism to allow the use of = in unnamed template arguments. Defining Template:= to expand to something other than = has been deprecated since 1.36, with affected pages put into a special tracking category for migration.
  • Bot passwords are now supported when using the REST API.
  • Usage of var() CSS function in inline styles has been re-enabled.

External libraries

  • Upgrade jQuery from 3.6.0 to 3.6.1.
  • Removed jquery.jStorage, deprecated since MW 1.28; use instead.

Official release notes

For more information about the changes, check the official release notes:

See also

Further help and feedback