The HHVM error log, after upgrade to 3.12, is full of warnings about array to string or scalar to array conversion:
```Warning: Cannot use a scalar value as an array in /var/www/wiki/w/includes/jobqueue/JobQueueGroup.php on line 30```
```Notice: Array to string conversion in /var/www/wiki/w/extensions/Scribunto/engines/LuaSandbox/Engine.php on line 3```
```Notice: Array to string conversion in /var/www/wiki/w/includes/libs/objectcache/APCBagOStuff.php on line 96```
```Notice: Array to string conversion in /var/www/wiki/w/includes/Sanitizer.php on line 1044```
There are additional type mismatch warnings in stacktraces after frequent segmentation faults (which dodn't make it into the log) like:
```AbstractContent->getParserOutput(Традиция:Идеи/Традиция, 399847, Object of class ParserOptions could not be converted to string) called at [/var/www/wiki/w/includes/poolcounter/PoolWorkArticleView.php:140]```
```MediaWiki->performAction(Object of class Article could not be converted to string, Традиция:Идеи/Традиция) called at [/var/www/wiki/w/includes/MediaWiki.php:287]```