I am also getting this same error but the solution offered by hubertv can’t work as I only appear to have 1 avbin.dll on my machine. I am running psychopy on 2 machines and get the error on both.
First machine: 32-bit windows desktop, psychopy version 1.85.3, avbin.dll is in C:\Windows\System32.
Second machine: 64-bit windows desktop, psychopy version 1.85.3, avbin.dll is in C:\Windows\SysWOW64.
This error has only popped up since I updated psychopy to 1.85.3. It isn’t causing scripts to crash that I can tell, the error just appears at either the start or end of running experiments, but it’s a bit concerning in case it will affect future tasks.