Upload to mainframe fails after upgrade from 5.11.3 to 5.13.1 (or 5.12 beta) with Permission denied

After upgrading from v 5.11.3 to any above version, including 5.13.1, I am unable to upload files to one specific destination. Login goes well, but when performing a put command, I get:

Permission denied.
Error code: 3
Error message from server: Permission denied

All I know about the destination host is that it's not a regular SFTP server, but a mainframe. The provider claims that WinSCP is a supported client.

I've attached logs from a successful upload using v. 5.11.3 and a failed upload using 5.13.1.


Thanks in advance!

What does the //DTS4.UP.G4T15.S60290 mean?

This is the full path of the destination file. Because it's a mainframe, it doesn't use the normal path notion //folder/file.ext, but instead just a "target".

Any news on this?

Sorry, I've missed your answer. Though it does not explain the double slash.

I would expect it to indicate the home directory of the user, but our provider has not documented it.

I'd need a test account to debug this problem. Is it possible?