Migration from Owncloud doesnt start - error:"Could not open updater.log"

Hi there,

after spending half a day to update my OC running on my diskstation from 8.x through all major releases up to, i am stuck short before reaching the goal of day, to migrate to NC.

Trying to start the migration process by typing MYOWNCLOUD/updater/index.php ends with the message above. I downloaded this file on my computer and uploaded it via file station, as well as downloading it directly to my diskstation via terminal. Doesnt work.

Strange, cause when I tried it unter OC 9.1.8 the assistent at least started, though process was abortet, cause it couldnt find a update path…
So if anyone has an idea about it, I am more than happy to read about it and try…