error after migration to joomla 4 on admin home page

hi there,

[problem]
I'm currently upgrading 50+ joomla 3 websites to joomla 4.
The websites are all very very very similar under the hood.
Everything works fine on almost all websites, but on one website I get this error after migration on adminstrator's home page:

[error]
An error has occurred.
    0 Joomla\Plugin\Quickicon\Joomlaupdate\Extension\Joomlaupdate::getCoreUpdateNotification(): Argument #1 ($event) must be of type Joomla\Module\Quickicon\Administrator\Event\QuickIconsEvent, Joomla\Event\Event given, called in C:\MAMP\htdocs\[...]\libraries\vendor\joomla\event\src\Dispatcher.php on line 486

[Call stack]
#     Function     Location
1     ()     JROOT\plugins\quickicon\joomlaupdate\src\Extension\Joomlaupdate.php:93
2     Joomla\Plugin\Quickicon\Joomlaupdate\Extension\Joomlaupdate->getCoreUpdateNotification()     JROOT\libraries\vendor\joomla\event\src\Dispatcher.php:486
3     Joomla\Event\Dispatcher->dispatch()     JROOT\libraries\src\Application\EventAware.php:111
4     Joomla\CMS\Application\WebApplication->triggerEvent()     JROOT\administrator\modules\mod_flexiadmin\helper.php:168
5     modFlexiadminHelper::getIconFromPlugins()     JROOT\administrator\modules\mod_flexiadmin\mod_flexiadmin.php:37
6     include()     JROOT\libraries\src\Dispatcher\ModuleDispatcher.php:52
7     Joomla\CMS\Dispatcher\ModuleDispatcher::Joomla\CMS\Dispatcher\{closure}()     JROOT\libraries\src\Dispatcher\ModuleDispatcher.php:55
8     Joomla\CMS\Dispatcher\ModuleDispatcher->dispatch()     JROOT\libraries\src\Helper\ModuleHelper.php:281
9     Joomla\CMS\Helper\ModuleHelper::renderRawModule()     JROOT\libraries\src\Helper\ModuleHelper.php:161
10     Joomla\CMS\Helper\ModuleHelper::renderModule()     JROOT\administrator\components\com_cpanel\tmpl\cpanel\default.php:61
11     include()     JROOT\libraries\src\MVC\View\HtmlView.php:410
12     Joomla\CMS\MVC\View\HtmlView->loadTemplate()     JROOT\libraries\src\MVC\View\HtmlView.php:203
13     Joomla\CMS\MVC\View\HtmlView->display()     JROOT\administrator\components\com_cpanel\src\View\Cpanel\HtmlView.php:158
14     Joomla\Component\Cpanel\Administrator\View\Cpanel\HtmlView->display()     JROOT\libraries\src\MVC\Controller\BaseController.php:645
15     Joomla\CMS\MVC\Controller\BaseController->display()     JROOT\administrator\components\com_cpanel\src\Controller\DisplayController.php:56
16     Joomla\Component\Cpanel\Administrator\Controller\DisplayController->display()     JROOT\libraries\src\MVC\Controller\BaseController.php:678
17     Joomla\CMS\MVC\Controller\BaseController->execute()     JROOT\libraries\src\Dispatcher\ComponentDispatcher.php:143
18     Joomla\CMS\Dispatcher\ComponentDispatcher->dispatch()     JROOT\libraries\src\Component\ComponentHelper.php:361
19     Joomla\CMS\Component\ComponentHelper::renderComponent()     JROOT\libraries\src\Application\AdministratorApplication.php:143
20     Joomla\CMS\Application\AdministratorApplication->dispatch()     JROOT\libraries\src\Application\AdministratorApplication.php:186
21     Joomla\CMS\Application\AdministratorApplication->doExecute()     JROOT\libraries\src\Application\CMSApplication.php:293
22     Joomla\CMS\Application\CMSApplication->execute()     JROOT\administrator\includes\app.php:61
23     require_once()     JROOT\administrator\index.php:32

[details]
I can switch the error on and off by disabling/enabling Flexicontent.
I can not switch the error on and off by disabling/enabling any other extension.

[what i already tried with no success]
I tried installing flexicontent-cck-4.1.5.zip before migration.
I tried installing flexicontent-cck-4.1.5.zip after migration, then updating using joomla updater.

[setup]
joomla 3.10.12 > 4.3.4
FC 4.2.1
php 8.1.12
local mamp server on windows 11

How can i fix this error? Thansk a lot! Ben

hello you need to update flexi admin module
github.com/micker/mod_flexiadmin/releases/tag/v2-6

Great, that helped, thank you!

with pleasure