@mak.lo: Thanks for your report.

Can you send me an email, so I can send you back a debug version of WinSCP to track the problem? Please include a link back to this topic in your email. Also note in this topic that you have sent the email. Thanks.

I'm having the same issue. Although I think the files I am dropping over to WinSCP seem to be large even though they are compressed :/

@shellyleong: So please upgrade. You are not using the latest version of WinSCP.

Hi,
I'm currently using WinSCP version 5.17.6.10516, recently I'm hitting the issue upon downloading the file, it keeps show me not responding. Can please send me the debug WinSCP version? thanks.

Hi @martin,

you rock – the development version you created does not have the issue! I cross checked with the latest version 5.19.5 (Build 11933 2021-11-25): WinSCP gets frozen if I have a CIFS 1.0 shared drive connected (which I know is no longer supported with Win10, but that's another story). The development version works as expected.

Thanks a lot for your support!

@hi-ko: I have done some improvements:
Issue 2054 – Prevent hang when dragging files without drag&drop shell extensions when some mapped network drive is not available

I'm sending you an email with a development version of WinSCP to the address you have used to register on this forum.

There are technical reasons why WinSCP has to start monitoring all drives, when you are dragging files, so it can detect where you drop them too. Though this is needed only if you have opted not to install WinSCP drag&drop shell extension (or when you are using portable version of WinSCP or Microsoft Store installation).
See also https://beta.winscp.net/eng/docs/ui_pref_dragdrop#fake_file

Indeed, that's already a suspect I had in mind but did not manage to reproduce yet.
My guess it's either an issue with a network drive which still uses SMBv1 (which has issues under Win10 because Win10 unfortunately always tries SMBv2 to reconnect) or IPv4/IPv6 issues when connecting/disconnecting from a IPv4 only VPN connection.
Anyway – shouldn't WinSCP behave like Windows Explorer: only access a network drive if you click on it?

The problem might be related to availability of network drives (if you have any). Would this help with reproducing the issue?

Hi Martin,

thanks for providing the debug version. Unfortunately today I was not able to reproduce the issue although it was easy to reproduce last week – even after reboots. I will keep the debug version and once I'm able to reproduce the issue I will report back.

@hi-ko: Thanks for your report.
I have sent you an email with the debug version too.

Hi @martin,

if you need another user to generate debug output: I have a similar issue with the latest version (5.19.5 (Build 11933 2021-11-25): Once I drag & drop files from a specific server WinSCP seems to hang and Antimalware Service Executable shows high load. I need to logout or to reboot to get back a working system: Win10 Prof Version 21H 1 (Build 19043. 1348).