Edited files uploads (empty files are uploaded)

OS: Win 10 Ent.
WinSCP Version: 5.17 (updated today 2020-02-24 from v. 5.15.9).
Tried to save modifications of an edited file (with Npp++). File upload result is the screenshot attached.
A file with the same name has been uploaded but the size was 0 bytes
Never had this problem before with previous versions.
Regards.

Can you post (English) session log files on Debug 2 log level both from 5.17 and 5.15.9 showing the same upload?

I uninstalled V5.17 and reinstalled v.5.15.9 after this problem...
Anyway, the problem can be reproduced.
Set language to English and performed the same actions that caused the problem with Debug 2 logging enabled (file V_5-15-9.log).
Unistalled v.5.15.9 and reinstalled v. 5.17 with same log settings (file V_5-17.log).
The actions performed with the 2 versions are exactly the same.
Notice that not with all files this happens.
Starting from row #1344 in the file V_5-17.log, is logged another update for a different file (not .php but .json) and everything worked properly.
There is a screenshot too, but in english this time...
Hope this can help you.
Thanks in advance, Nestor.

We can reproduce the bug. In the log you can find the code 451. The data connection aborts. Only TLS 1.3 connections are affected. TLS 1.2 works perfectly. It seams the bug only occurs when the filesize is bigger than 10 kB.

This issue has been added to the tracker:
Issue 1831 – TLS session resumption is not working for FTP transfers with TLS 1.3

This seems to be a separate issue:
Issue 1834 – FTP file uploads are interrupting with TLS 1.3