Thread:Project:Support desk/ Compilation failed: group name must start with a non-digit at offset/reply (3)

Yes, integrating this patch into your source code should solve the problem. Relevant is only the part inside the file includes/MagicWord.php; the line numbers may be different in 1.20.

However, if I were you I would do something else: I would update MediaWiki. Your version 1.20.3 has known security holes and is no longer maintained. In contrast, current versions of MediaWiki are secure and they already include this fix.

See Upgrade for a complete guide on how to do an upgrade!