David,
Thanks for your response!
I parsed the expert section but I have not found any message suggesting that the updraft directory is not writable.
But it seems your suggestion is very close to the problem, because now I also experienced problems with uploading a document to the server. Several times it seemed successful but then this document on the server appeared to be corrupted! Same when trying this with FTP (FileZilla). Later today I managed once to upload a document successfully.
However backing up with UpdraftPlus, (much larger files involved), still results in a bunch of zip-errors, sometimes the process stocks, sometimes it ends saying Backup Successfully but with errors which is not confidence inspiring.
So the problem seems to be a lack of proper communication with the server!
Do you want me to send you the UpdraftPlus log file? If yes, how can I mail you this?
Regards,
Jan Adriaansen