Hello everyone,

Following the migration of a site from J3 to J4 I thought I had resolved all the bugs but I hadn't seen any major ones...
Everything works except user management... Which is quite annoying...
There is Community builder to install in its latest version 2.9, Joomla is in v4.4 and the PHP version is in 8.1.
As soon as I click on a user I get the error:

An error has occurred
0 Call to undefined method Joomla\CMS\Application\AdministratorApplication::i sAdmin()
Call stack#FunctionLocation1()JROOT/administrator/components/com_acymailing/compat/joomla.php:3182acymailing_isAdmin()JROOT/plugins/system/regacymailing/regacymailing.php:563plgSystemRegacymailing->onAfterRoute()JROOT/libraries/src/Plugin/CMSPlugin.php:2894Joomla\CMS\Plugin\CMSPlugin->Joomla\CMS\Plugin\{closure}()JROOT/libraries/vendor/joomla/event/src/Dispatcher.php:4865Joomla\Event\Dispatcher->dispatch()JROOT/libraries/src/Application/EventAware.php:1116Joomla\CMS\Application\WebApplication->triggerEvent()JROOT/libraries/src/Application/AdministratorApplication.php:4547Joomla\CMS\Application\AdministratorApplication->route()JROOT/libraries/src/Application/AdministratorApplication.php:1718Joomla\CMS\Application\AdministratorApplication->doExecute()JROOT/libraries/src/Application/CMSApplication.php:2939Joomla\CMS\Application\CMSApplication->execute()JROOT/administrator/includes/app.php:6110require_once()JROOT/administrator/index.php:32When I go to community builder, there I can enter the user file but the error occurs when I click on save or save and close...

An error has occurred
0 Call to undefined method Joomla\CMS\Application\AdministratorApplication::i sAdmin()
Call stack#FunctionLocation1()JROOT/administrator/components/com_acymailing/compat/joomla.php:3182acymailing_isAdmin()JROOT/plugins/system/regacymailing/regacymailing.php:7933plgSystemRegacymailing->onAfterStoreUser()JROOT/plugins/system/regacymailing/regacymailing.php:7634plgSystemRegacymailing->onUserAfterSave()JROOT/libraries/src/Plugin/CMSPlugin.php:2895Joomla\CMS\Plugin\CMSPlugin->Joomla\CMS\Plugin\{closure}()JROOT/libraries/vendor/joomla/event/src/Dispatcher.php:4866Joomla\Event\Dispatcher->dispatch()JROOT/libraries/src/Application/EventAware.php:1117Joomla\CMS\Application\WebApplication->triggerEvent()JROOT/libraries/src/User/User.php:7678Joomla\CMS\User\User->save()JROOT/libraries/CBLib/CB/Database/Table/UserTable.php:6289CB\Database\Table\UserTable->store()JROOT/libraries/CBLib/CB/Database/Table/UserTable.php:117510CB\Database\Table\UserTable->saveSafely()JROOT/administrator/components/com_comprofiler/controller/controller.user.php:17111CBController_user->saveUser()JROOT/administrator/components/com_comprofiler/admin.comprofiler.controller.php:28912require()JROOT/administrator/components/com_comprofiler/comprofiler.php:1413require_once()JROOT/libraries/src/Dispatcher/LegacyComponentDispatcher.php:7114Joomla\CMS\Dispatcher\LegacyComponentDispatcher::J oomla\CMS\Dispatcher\{closure}()JROOT/libraries/src/Dispatcher/LegacyComponentDispatcher.php:7315Joomla\CMS\Dispatcher\LegacyComponentDispatcher->dispatch()JROOT/libraries/src/Component/ComponentHelper.php:36116Joomla\CMS\Component\ComponentHelper::renderCompon ent()JROOT/libraries/src/Application/AdministratorApplication.php:14317Joomla\CMS\Application\AdministratorApplication->dispatch()JROOT/libraries/src/Application/AdministratorApplication.php:18618Joomla\CMS\Application\AdministratorApplication->doExecute()JROOT/libraries/src/Application/CMSApplication.php:29319Joomla\CMS\Application\CMSApplication->execute()JROOT/administrator/includes/app.php:6120require_once()JROOT/administrator/index.php:32So I need help... I thought it was a compatibility issue with another component so I updated everything and deactivated as much stuff as possible but nothing helped. ..
Thank you so much