Thread:Project:Support desk/Problems after upgrading to 1.22 Segfault / zend_mm_heap corrupted / Allowed memory size of 134217728 bytes exhausted (tried to allocate <very large number> bytes) in includes/context/RequestContext.php on line 350 (the very large number is typically in the range 8Gb - 20 Gb)
Error installing MW 1.27 - Exception encountered, of type "Wikimedia\Assert\ParameterAssertionException". Bad value for parameter maxKeys: must be above zero, in objectcache/HashBagOStuff.php
Topic:T75cloz7981b8i92 - Can't login or create user after upgrade to 1.27. New session generated on every request, apparently "sessions stored on a non-persistent storage"
Topic:T70tn1irrw8ny8ts Exception encountered, of type "Wikimedia\Assert\ParameterAssertionException" - Bad value for parameter maxKeys: must be above zero. Problem with "strato.de" hosting servers.
Topic:Tql84zdcz2p8cctk postfix/sendmail: fatal: Recipient addresses must be specified on the command line or via the -t option (resolved)
VisualEditor: HTTP 400 errors trying to talk to rest.php: "The 'Promise-Non-Write-API-Action' HTTP header was sent but the request was to an API write module."
On IRC: Solved it - and it was the most stupid thing I overlooked: rest.php wasn't symlinked, so index.php was handling it. Add that link and all is well
Empty pages after upgrade to 1.35
Lots of previous threads that I haven't bothered to collect
logging table without log_user_text. This may happen if your wiki comes from a pre-1.16 version. MediaWiki is trying to apply the actor migration before creating the column...