FTP: never work "Retry" button in dialog "Error transferring"

Never work "Retry" button in dialog windows with content:

Error transferring file 'path to file'

Copying file to remote side failed.
file.name: Append/Restart not permitted, try again

Abort | Retry | Skip | Skip all | Help

Have to press "Skip" and reSave file again (via external editor)...

Please post a log file showing failed attempt, followed by successful one, after you re-save the file.

Related improvement:
Issue 2194 – Support for ProFTPD command OPTS REST STOR to query if upload restart is possible