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

<Try to describe precise steps that lead to the problem (where do you click, what keys do you press, what do you see, etc.)>
<If relevant, consider attaching a session log file or a screenshot)>

This mostly happens when I try to open or write into a file in the server.

WinSCP 5.6.2

Error message:
External exception 80000101

Stack trace:
(F7783425) WinSCP.exe.[F7784425]
(000689FA) ntdll.dll.[7BC799FA]
(00068E5E) ntdll.dll.[7BC79E5E]
(0006B2C9) ntdll.dll.[7BC7C2C9]
(0006B722) ntdll.dll.[7BC7C722]

Status: not_matched

I know how to reproduce the problem or the problem happens frequently enough. I wish to be contacted by the WinSCP team to help resolving the problem.