Thank you very much for reply. Once we double click the exe file of debug version, error message pop up and didn't create any log file. Already emailed back to you, thank you!

Thanks for your report.
I have sent you an email with a debug version of WinSCP to the address you have used to register on this forum.

Hi, The situation we encountered is as following:

1. WinSCP Version: 5.19.6
   
   
2. WinSCP.exe used to start fine, but without any Windows OS update or folder permission change, it suddenly has following error message.
   
   The Mandarin Message means 'has stopped running'）
   
   
   
3. We've used the WinSCPnet dll on C# code of .NET Framework 4.5, it also throws error suddenly at the same time. It runs locally on Visual Studio 2019 and worked fine on the day before.
   
   
   
   
   
4. Other Computer with the same environment, WINSCP.exe and Code are all good so far.
   Is there any thought about this situation? Any help is appreciated, thank you.