Can not delete one file!?

Hi, I have a problem with my ownCloud.

I have a zip file and would like to delete this. If I do this it will be deleted locally but not online.
If I want to delete the file via the web interface I always get the message:
"Failed to delete file" file.zip ""

How can I solve the problem?

Extract from the LOG:
Exception: {"Message":"HTTP\/1.1 423 \"Datei.zip\" is locked","Exception":"OCA\DAV\Connector\Sabre\Exception\FileLocked","Code":0,"Trace":"#0 \/www\/htdocs\/wwwwwwww\/ownCloud\/3rdparty\/sabre\/dav\/lib\/DAV\/Tree.php(179): OCA\DAV\Connector\Sabre\File->delete()\n#1 \/www\/htdocs\/wwwwwwww\/ownCloud\/3rdparty\/sabre\/dav\/lib\/DAV\/CorePlugin.php(285): Sabre\DAV\Tree->delete('Dat...')\n#2 [internal function]: Sabre\DAV\CorePlugin->httpDelete(Object(Sabre\HTTP\Request), Object(Sabre\HTTP\Response))\n#3 \/www\/htdocs\/wwwwwwww\/ownCloud\/3rdparty\/sabre\/event\/lib\/EventEmitterTrait.php(105): call_user_func_array(Array, Array)\n#4 \/www\/htdocs\/wwwwwwww\/ownCloud\/3rdparty\/sabre\/dav\/lib\/DAV\/Server.php(459): Sabre\Event\EventEmitter->emit('method:DELETE', Array)\n#5 \/www\/htdocs\/wwwwwwww\/ownCloud\/3rdparty\/sabre\/dav\/lib\/DAV\/Server.php(248): Sabre\DAV\Server->invokeMethod(Object(Sabre\HTTP\Request), Object(Sabre\HTTP\Response))\n#6 \/www\/htdocs\/wwwwwwww\/ownCloud\/apps\/dav\/appinfo\/v1\/webdav.php(56): Sabre\DAV\Server->exec()\n#7 \/www\/htdocs\/wwwwwwww\/ownCloud\/remote.php(164): require_once('\/www\/htdocs\/www...')\n#8 {main}","File":"\/www\/htdocs\/wwwwwwww\/ownCloud\/apps\/dav\/lib\/Connector\/Sabre\/File.php","Line":342,"User":"USER"}

Best regards

There is a FAQ available at [1] explaining the needed steps.

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