Your software
My Mautic version is: 4
My PHP version is: 7.4.3
My Database type and version is: 8.0.28-0ubuntu0.20.04.3
Your problem
My problem is: I’ve tried to change from the default Dashboard reports to another pre-existing template. Now my Dashboard shows the “We’ve found a bug” error message and I can’t turn it back.
[2022-03-11 16:37:03] mautic.CRITICAL: Uncaught PHP Exception Symfony\Component\Debug\Exception\FatalThrowableError: "Call to a member function createQueryBuilder() on null" at /xxxxxx/mautic/app/bundles/EmailBundle/Stats/Helper/FilterTrait.php line 31 {"exception":"[object] (Symfony\\Component\\Debug\\Exception\\FatalThrowableError(code: 0): Call to a member function createQueryBuilder() on null at /xxxxxx/mautic/app/bundles/EmailBundle/Stats/Helper/FilterTrait.php:31)"} []
You mentioned dashboard above but the error comes from email bundle. I am not so sure I can visualize a problem as well as I thought at first. Could you please provide some screenshots from the GUI (are we talking about widgets or reports - or maybe even something else).
At first glance nothing obvious comes to mind, so it might be a bug.