I checked "I know how to reproduce this problem" because this looks like a similar problem I had in the past which was eventually fixed. (I think that this may be a regression, share some underlying cause, and/or have a similar cause.)
I just upgraded to this latest version of WinSCP, so this occurred on the first night this new version of WinSCP was left running on my idle PC.
At night I disable networking (via Windows Control Panel). In a prior version of WinSCP, this caused a crash regularly, by not deterministicly - like maybe a race condition. However, the version I was using most recently prior to yesterday's upgrade had never crashed this way.
I run WinSCP with Pagent, and in this case the other end of the link was a local Centos 7 machine just recently updated.
To reproduce this problem: I opened WinSCP yesterday morning (after letting it upgrade.) I uploaded & downloaded some files, and otherwise left WinSCP idle most of the day. Several times during the day, I disabled the network (it helps FireFox get its act back together - I have LOTS of tabs open.) None of these network shutdowns during the day triggered a crash, but after I again shutdown the network overnight, I came in this morning to this crash. Based on this, it would appear that the crash is not deterministic, so reproducing it may take longer on any individual run.
Hope this helps - Thanks for all your work on WinSCP
Invalid access to memory.
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.