User of Mac OS ver 10.15.4 Catalina here. I have the same problem. Galaxy worked on my mac for once after I have installed it and never after.

If you're installing in a remote desktop window, ifilgud's post above has the answer.

I just updated Windows 10 to v2004, and this happened. Wish I saw this first before I reinstalled GOG Galaxy and the issue just reappeared. Going into services and switching GalaxyCommunication back to Automatic indeed fixed the issue.

I're RIGHT! It worked for me, I love you :)

Didn't work for me. I set Galaxy to automatic and it still give me the bull warning, which won't let me get rid of it even though GoG is running fine and I can use it with the warning hidden behind GoG, but if I X it away or click okay it seems to force crash GoG Launcher even though it is working.

I'm getting this on a fresh install of Galaxy on a very vanilla Win10 install.

Since it's a completely fresh install, I don't imagine reinstalling will help..?

From searching forums, seems like this has been an ongoing issue for *years*, why is it still a problem?

I do not have "CryptoPrevent", and running C:\ProgramData\GOG.com\Galaxy\redists\GalaxyCommunication.exe seems to have no effect.

galaxy what a wonderful app :P

I'm having the same issue; this seems to come up and I've tried everything including:
Reinstalling GoG
Reinstalling my Windows 10 installation
Running C:\ProgramData\GOG.com\Galaxy\redists\GalaxyCommunication.exe on start of GoG.
Running C:\ProgramData\GOG.com\Galaxy\redists/GalaxyCommunication.exe on its own to see if there are any errors on start up (nothing seems to happen).
Uninstalling GoG, deletting anything related to GOG in C:\ProgramData and %APPDATA% and E:\Program Files (x86)\GOG Galaxy (I install to E: as that is my game drive).
Tried setting GalaxyCommunication service to Automatic.

There are countless other posts above me with similar issues; but no comment from GoG at all; so are we to assume there is no fix and I should just stop using GoG and go elsewhere for games?

I'm getting this error as well. It worked back in october but has stopped working:

2020-12-07 10:20:36.212 [Information][ (0)] [TID 19448][comm_service]: Log started. Application version: 1.2.43.23 (2020-02-11 12:26).
2020-12-07 10:20:36.213 [Information][ (0)] [TID 19448][comm_service]: Operating system: Windows 8 6.2 (Build 9200) (IA32)
2020-12-07 10:20:36.537 [Warning][ (0)] [TID 19448][comm_service]: SessionID is not equal to ActiveConsoleSessionId while getting process token from process explorer.exe, error code= 0
2020-12-07 10:20:36.538 [Warning][ (0)] [TID 19448][comm_service]: Failed getting token for process explorer.exe, checked processes: 248.
2020-12-07 10:20:36.538 [Error][ (0)] [TID 19448][comm_service]: Failure getting the explorer.exe token. Last error code: 0
2020-12-07 10:20:36.538 [Warning][ (0)] [TID 19448][comm_service]: GetCurrentUserSID() failed

I contacted support and they answered withing a short time frame. In my case this was likely caused by the firewall. I added exceptions to GalaxyClient, GalaxyClientService and GalaxyCommunication to firewall exceptionlist.

I also added GOG Galaxy folder and ProgramData\GOG.com\Galaxy\redists to anti virus exclusions.

If you have Hyper-V enabled, try turning it off, it worked for me.

tried everything including firewall exceptions, uninstalling. disabling hyper v worked.

ALL of the "fixes" so far have done nothing to change what is happening.

There has NEVER been an issue with this program before, EVER.

Nothing has changed at my end to warrent this happening now.

Doesn't matter what I do, nothing works.

I now have a GoG account that I am unable to use anymore...

Um... what do you mean, you're unable to use your account anymore?
You don't need the galaxy client to access your account.
Just download your games normally, form your account here - https://www.gog.com/account