TYPO3 Core

You can not edit templavoila Template Object if his preview icon is missing!
Bug is in TYPO3\CMS\Backend\Utility\BackendUtility -> thumbCode() method.

In this part, if you don't get a file (file is missing) next line is trying to read File extension and throws an error!

$fileName = trim($uploaddir . '/' . $theFile, '/');
$fileObject = \TYPO3\CMS\Core\Resource\ResourceFactory::getInstance()->retrieveFileOrFolderObject($fileName);//if file is missing fileObject is empty
$fileExtension = $fileObject->getExtension(); // and this throws exception

Just need to double check if $fileObject is empty and then go further.

if($fileObject) {
$fileExtension = $fileObject->getExtension();
.......
}

Bug found in versions: 6.1.4-dev and 6.1.5

Patch set 2 for branch TYPO3_6-1 of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/26446

Patch set 3 for branch TYPO3_6-1 of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/26446