The deployment of MediaWiki 1.29.0-wmf.9 is currently blocked and all wikis have been reverted to wmf.8. This latest revert is due to excessive warnings which appeared in logs immediately after deploying to group2. The warnings all read as follows: Warning: Empty regular expression in /srv/mediawiki/php-1.29.0-wmf. 9/includes/parser/DateFormatter.php on line 200 This issue is tracked in https://phabricator.wikimedia.org/T156364 and currently blocks further deployments. More background: A similar flood of log spam occurred after deploying the branch to group1, however, the problem subsided after a while and did not reappear until Thursday's deployment. There have been recent changes to DateFormatter.php, however, the changes do not appear to be the direct culprit. In fact, after rolling back the changes, a different message appears in the log, however, with less frequency than the line 200 error. Several engineers have looked at this issue but so far we have not isolated the root cause. Additional eyes on this issue would be welcomed and further discussion should be directed to Phabricator. In the interest of keeping everyone in the loop, I will follow up in this thread if/when there is a resolution. Regards, Mukunda --- Mukunda Modell Wikimedia Release Engineering