Happens with php maintenance/update.php and with manual re-caching on (I think, because it works on my test wiki where it is off)

...
Deleting old default messages (this may take a long time!)...No localisation cache found for English. Please run maintenance/rebuildLocalisationCache.php.
Backtrace:
#0 /var/www/w/includes/LocalisationCache.php(242): LocalisationCache->initLanguage('en')
#1 /var/www/w/includes/LocalisationCache.php(205): LocalisationCache->loadItem('en', 'namespaceNames')
#2 /var/www/w/languages/Language.php(241): LocalisationCache->getItem('en', 'namespaceNames')
#3 /var/www/w/languages/Language.php(289): Language->getNamespaces()
#4 /var/www/w/includes/Title.php(470): Language->getNsText(2)
#5 /var/www/w/includes/Title.php(277): Title::makeName(2, 'MediaWiki defau...', '')
#6 /var/www/w/includes/User.php(456): Title::makeTitleSafe(2, 'MediaWiki defau...')
#7 /var/www/w/includes/User.php(251): User::idFromName('MediaWiki defau...')
#8 /var/www/w/includes/User.php(1425): User->load()
#9 /var/www/w/includes/User.php(2053): User->getId()
#10 /var/www/w/maintenance/deleteDefaultMessages.php(43): User->addGroup('bot')
#11 /var/www/w/maintenance/updaters.inc(1148): DeleteDefaultMessages::reallyExecute()
#12 /var/www/w/maintenance/update.php(42): do_all_updates(false, true)
#13 {main}

Version: 1.16.x
Severity: major