Topic on Project:Support desk

Since some months our wiki (MW 1.31.5) experiences a strange error, that happens maybe twice a week (on average).

The php error log is as follows:

[06-Dec-2019 10:02:16 CET] PHP Fatal error:  Uncaught Error: Call to a member function getCode() on null in /html/site/mediawiki/includes/user/User.php:1737
Stack trace:
#0 /html/site/mediawiki/includes/user/User.php(5417): User::getDefaultOptions()
#1 /html/site/mediawiki/includes/user/User.php(3101): User->loadOptions()
#2 /html/site/mediawiki/includes/context/RequestContext.php(336): User->getOption('language')
#3 /html/site/mediawiki/includes/Message.php(380): RequestContext->getLanguage()
#4 /html/site/mediawiki/includes/Message.php(1290): Message->getLanguage()
#5 /html/site/mediawiki/includes/Message.php(842): Message->fetchMessage()
#6 /html/site/mediawiki/includes/Message.php(934): Message->toString('text')
#7 /html/site/mediawiki/includes/exception/MWExceptionRenderer.php(201): Message->text()
#8 /html/site/mediawiki/includes/exception/MWExceptionRenderer.php(301): MWExceptionRenderer::msg('dberr-problems', 'Sorry! This sit...')
#9 /ht in /html/site/mediawiki/includes/user/User.php on line 1737

Sometimes this error happens once a day, sometimes several times within one minute.

As a consequence the site is down for some seconds and editors get kicked out (logged out) of the wiki.

I googled the error messages several times, but didn't find anything helpful.

Who can point me in the right direction to fix this annoying error please?

The site in question is https://secret-wiki.de/wiki/Spezial:Version and has ~ 60.000 visitors monthly, but this error also happens occasionally on another public MW 1.31 install that I run.

Topic:Tuljdjm52dgz78ao and Topic:U6swsyaakfze4woh look a bit similar?

so it looks like the error (about getCode) happens when trying to show an error message about not being able to connect to database. Perhaps your dayabase server is unstable or overloaded (maybe it hit max concurrent users or something). Unfortunately the error you posted doesnt have details, but maybe there is more fmdetails in debug log or something