Same Problem!
New and Clean install!
Can´t delete old Images, same Failure!
EDIT1: (not solved)
Now i found a Solution!
Configuration Manager / Software Repositories
I edit the FTP Login from Raport User to Administrator and it works!
I don´t know why the RaportUser didn´t work!
EDIT12: (solved)
You need the Rapport User!
Because you can´t update the Device.
The device use the Rapport User to connect the FTP Repository.
In my case the Password of the Rapport User was expired.
I set the Password r@p8p0r+ and check the Password never expired and uncheck the user must change.
Then correct it in the Repository Master and now work all the stuff!
I hope this is the complete Solution.
To configure the FTP see this link: