Cant access Account settings in icingaweb2

  • Icinga Web 2 version: 2.9.3

  • Used modules and their versions (System - About):
    |Name|Version|
    |—|—|
    |director|master|
    |doc|2.9.3|
    |grafana|1.4.2|
    |incubator|0.6.0|
    |ipl|v0.5.0|
    |migrate|2.9.3|
    |monitoring|2.9.3|
    |reactbundle|0.9.0|

  • Web browser used: Chrome 92.0.4515.159

  • Icinga 2 version used (icinga2 --version): r2.13.1-1

  • PHP version used (php --version): PHP 7.4.21

  • Server operating system and version: Debian 11 Bullseye

Hello,
after upgrading from Buster, I suddenly get the followin error, when accessing my users Account Settings (/icingaweb2/account):

file_get_contents(): Filename cannot be empty

#0 [internal function]: Icinga\Application\ApplicationBootstrap->Icinga\Application\{closure}()
#1 /usr/share/icingaweb2/application/forms/PreferenceForm.php(214): file_get_contents()
#2 /usr/share/php/Icinga/Web/Form.php(776): Icinga\Forms\PreferenceForm->createElements()
#3 /usr/share/php/Icinga/Web/Form.php(1118): Icinga\Web\Form->create()
#4 /usr/share/icingaweb2/application/forms/PreferenceForm.php(171): Icinga\Web\Form->populate()
#5 /usr/share/php/Icinga/Web/Form.php(1209): Icinga\Forms\PreferenceForm->onRequest()
#6 /usr/share/icingaweb2/application/controllers/AccountController.php(78): Icinga\Web\Form->handleRequest()
#7 /usr/share/icingaweb2/library/vendor/Zend/Controller/Action.php(507): Icinga\Controllers\AccountController->indexAction()
#8 /usr/share/php/Icinga/Web/Controller/Dispatcher.php(76): Zend_Controller_Action->dispatch()
#9 /usr/share/icingaweb2/library/vendor/Zend/Controller/Front.php(937): Icinga\Web\Controller\Dispatcher->dispatch()
#10 /usr/share/php/Icinga/Application/Web.php(304): Zend_Controller_Front->dispatch()
#11 /usr/share/php/Icinga/Application/webrouter.php(107): Icinga\Application\Web->dispatch()
#12 /usr/share/icingaweb2/public/index.php(4): require_once(String)
#13 {main}

Does anyone know how to fix this error, or has encountered it before? Could this be caused, by the used PHP Version (7.4 since Debian 11). Everything else seems to work just fine in Icinga2 and Icinga2Web.

Thanks for all answers in advance

Might be related to this: https://github.com/Icinga/icingaweb2/issues/4512