Topic on Extension talk:CodeMirror/5

MW 1.35.6 / PHP 7.4.27 / CodeMirror 4.0.0

Despite the option being enabled, line numbering does not work.

$wgCodeMirrorLineNumberingNamespaces = [ NS_TEMPLATE ];

The feature didn't exist before MediaWiki 1.37.

MW 1.37.2 / PHP 7.4.27 / CodeMirror 4.0.0

The line numbering still does not work.

Try with $wgCodeMirrorLineNumberingNamespaces = null; → no more success.

The CodeMirror version number is not very meaningful, unfortunately. Are you sure you updated the extension? You can check if CodeMirror/extension.json contains "CodeMirrorLineNumberingNamespaces".