Invalid access to memory.

<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)>

WinSCP 5.2.3

Error message:
Invalid access to memory.

I had 2 connections open, and pressed disconnect on one of them.

Thanks for your report.
Are you able to reproduce the problem?