TYPO3 Core

I guess the method checkStoredRecord() fails and this returns then null. I am not so sure if changing the line
$newRow = $this->checkStoredRecord($table, $id, $fieldArray, 1);
to
$newRow =(array) $this->checkStoredRecord($table, $id, $fieldArray, 1);

is the proper solution?

Thanks a lot, this seems to fix the uncaught exception as described above.

I could create new pages now without problem.

However, whenever I try to add new content element on newly created page I receive following error:

Oops, an error occurred!

$uid must be positive integer, 0 given 
More information regarding this error might be available online (https://wiki.typo3.org/Exception/CMS/1437656456).

This is in error log:

Core: Exception handler (WEB): Uncaught TYPO3 Exception: #1437656456: $uid must be positive integer, 0 given | InvalidArgumentException thrown in file C:\inetpub\wwwroot\typo3\sysext\backend\Classes\Form\FormDataProvider\AbstractDatabaseRecordProvider.php in line 44. Requested URL: http://localhost/typo3/index.php?route=%%2Frecord%%2Fedit&token=a98a7395a75b4173d2e6ba88b268c8967c4f291d&edit[tt_content][3]=new&defVals[tt_content][colPos]=0&defVals[tt_content][sys_language_uid]=0&defVals[tt_content][CType]=header&returnUrl=%%2Ftypo3%%2Findex.php%%3Froute%%3D%%252Fweb%%252Flayout%%252F%%26token%%3D3f1624671e215145d02e8701a92c40f517bf50f8%%26id%%3D3 

There seems to already exist bug for this: https://forge.typo3.org/issues/83994

Is there any way to fix this? I have reinstalled typo3 after applying patches that fix uncaught exceptions and the $uid issue persists.

After applying patchset 3 from https://review.typo3.org/#/c/56118/ the "$uid must be positive integer, 0 given" issue was fixed.

However, there are errors while processing queries on Microsoft SQL Server. The bug is described here: https://forge.typo3.org/issues/84303