After TYPO3 Update from 6.2 to 7.6 still errors in TCA? - typo3

Question

I've made an update from TYPO3 CMS 6.2 to TYPO3 CMS 7.6.16. After a few problems with other extensions (tx_newsand third party ext.) and the changes in the TCA. Everything works fine after import live-dump ...
Upgrade wizard / Database compare
Update reference Index
Flush Cache and empty typo3temp
Deactivate and reactivate the Extensions with problems
Everything? Unfortunately, no. The extension doesn't work. I don't written the extension by myself. If I try to add a new data record in backend with this ext., I'll get this error:
An item in field form of table tx_blah_domain_model_job is not an array as expected
But the database comprare is finished. All tables are correct?!
Where's the problem? I know it's hard to analyze this without source code. There's a database field wrong, but why? It's the same database like before?
Where's the fault .. ext_tables.php or still sth. in TCA is wrong? I really need a tip .. its frustrating ..
EDIT: sys_log entry
Core: Exception handler (WEB): Uncaught TYPO3 Exception: #1439288036: An item in field form of table tx_blah_domain_model_job is not an array as expected | UnexpectedValueException thrown in file /typo3_src/typo3_src-7.6.16/typo3/sysext/backend/Classes/Form/FormDataProvider/AbstractItemProvider.php in line 1264.
EDIT 2: I think, there must be sth. in typo3conf/ext/blah/Configuration/TCA/tx_blah_domain_model_job.php
see TCA source code
and that's in line 1264
/**
* Sanitize incoming item array
*
* Used by TcaSelectItems and TcaSelectTreeItems data providers
*
* #param mixed $itemArray
* #param string $tableName
* #param string $fieldName
* #throws \UnexpectedValueException
* #return array
*/
public function sanitizeItemArray($itemArray, $tableName, $fieldName)
{
if (!is_array($itemArray)) {
$itemArray = [];
}
foreach ($itemArray as $item) {
if (!is_array($item)) {
throw new \UnexpectedValueException(
'An item in field ' . $fieldName . ' of table ' . $tableName . ' is not an array as expected',
1439288036
);
}
}
return $itemArray;
}

Answer 1

aTry to use this in the TCA tx_imappointments_domain_model_job.php
'form' => array(
'exclude' => 1,
'label' => 'LLL:EXT:im_appointments/Resources/Private/Language/locallang_db.xlf:tx_imappointments_domain_model_job.form',
'config' => array(
'type' => 'select',
'renderType' => 'selectSingle',
'items' => array(array('', 0)),
'foreign_table' => 'pages',
'foreign_table_where' => ' AND pages.pid = 293',
'minitems' => 0,
'maxitems' => 1,
),
),
'items' in 'form' has to be a array how your error message said:
https://docs.typo3.org/typo3cms/TCAReference/ColumnsConfig/Type/Select.html#items