The mw:New requirements for user signatures will begin on Monday, 6 July 2020. This is a change to MediaWiki software that will prevent editors from accidentally setting certain types of custom signatures, such as a custom signature that creates Special:LintErrors (such as
<span>...<span> instead of
<span>...</span>) or a signature that does not link to the local account.
Few editors will be affected. If you want to know whether your signature (or any individual editor) is okay, you can check your signature at https://signatures.toolforge.org/check You are not required to fix an invalid custom signature immediately. Starting Monday, editors will not be able to create new invalid signatures to Special:Preferences. Later, we will contact affected editors. Eventually, invalid custom signatures will stop working. There will be an announcement in m:Tech/News then. You can subscribe to m:Tech/News. You can also put mw:New requirements for user signatures on your watchlist.