I have exactly the same problem. I have no idea why launching a 64-bit application fails with optirun/primusrun.
The error description seems not to be valid because I have absolutely no Wine processes such as exe's, wineserver or any wine-related thing running on my system. I have checked this so many times that even suggesting this as a solution is completely irrelevant and off-topic in my case.
Running 64-bit application with Intel card works fine without issues.
The same behavior occurs with multiple 64-bit Playonlinux-based Wine prefixes. 32-bit prefixes are not affected in any way.
I suspect this is a driver issue. That's why I checked my Nvidia drivers. I have both 64-bit and 32-bit Nvidia drivers installed.
I am able to run 64-bit KDE environment purely with Nvidia card only.
The relevant Playonlinux output states as follows:
wine client error:0: version mismatch 490/489.
Your wine binary was not upgraded correctly,
or you have an older one somewhere in your PATH.
Or maybe the wrong wineserver is still running?
err:winecfg:WinMain failed to restart 64-bit L"C:\\windows\\system32\\winecfg.exe", err 1359
Application tried to create a window, but no driver could be loaded.
The explorer process failed to start.
[POL_Wine] Message: Wine return: 0
The error message is always the same (eg. references "mismatch 490/489" etc.)
It doesn't really matter whichever Wine version I try to use on Playonlinux. The error message stays the same whether I use 64-bit Wine 1.8, 1.7.55, 1.7.34 or any version installed from your official Wine version pool.
Running 32-bit Wine application with optirun works fine.
I've reached a dead-end. I doubt I can solve this problem on my own which is why I need help with it.
Edité par Fincer