I have this problem too and occurs only if i activate the “stay logged in” slider.
If I reload the page I can login and Icinga Web works perfectly
This is the databse used: mysql Ver 8.0.25-0ubuntu0.20.04.1 for Linux on x86_64 ((Ubuntu))
SQLSTATE[42000]: Syntax error or access violation: 1115 Unknown character set: ''
#0 [internal function]: PDO->exec()
#1 /usr/share/icinga-php/ipl/vendor/ipl/sql/src/Connection.php(82): call_user_func_array()
#2 /usr/share/icinga-php/ipl/vendor/ipl/sql/src/Connection.php(164): ipl\Sql\Connection->__call()
#3 /usr/share/icinga-php/ipl/vendor/ipl/sql/src/Connection.php(399): ipl\Sql\Connection->connect()
#4 /usr/share/icinga-php/ipl/vendor/ipl/sql/src/Connection.php(438): ipl\Sql\Connection->prepexec()
#5 /usr/share/php/Icinga/Web/RememberMe.php(231): ipl\Sql\Connection->insert()
#6 /usr/share/icingaweb2/application/forms/Authentication/LoginForm.php(142): Icinga\Web\RememberMe->persist()
#7 /usr/share/php/Icinga/Web/Form.php(1178): Icinga\Forms\Authentication\LoginForm->onSuccess()
#8 /usr/share/icingaweb2/application/controllers/AuthenticationController.php(83): Icinga\Web\Form->handleRequest()
#9 /usr/share/icingaweb2/library/vendor/Zend/Controller/Action.php(507): Icinga\Controllers\AuthenticationController->loginAction()
#10 /usr/share/php/Icinga/Web/Controller/Dispatcher.php(76): Zend_Controller_Action->dispatch()
#11 /usr/share/icingaweb2/library/vendor/Zend/Controller/Front.php(937): Icinga\Web\Controller\Dispatcher->dispatch()
#12 /usr/share/php/Icinga/Application/Web.php(304): Zend_Controller_Front->dispatch()
#13 /usr/share/php/Icinga/Application/webrouter.php(107): Icinga\Application\Web->dispatch()
#14 /usr/share/icingaweb2/public/index.php(4): require_once(String)
#15 {main}