For me it works when I launch Galaxy 2.0 while not connected to the internet, then go online again.

Out of the sudden I've started getting the same issue. At first I could install a game that I've just purchased.
So a quick restart of the app, and then not only was I logged out but - after a successful login, I'm getting this error. Not cool :(

It's pretty ridiculous that a remote login causes an app to crash. Why would that even happen? I've never seen it with any other app save an actual game that got thrown off by the virtual video driver used in RDP. That doesn't seem to be happening here, where the error indicates a networking problem or problem of communication between two Galaxy components.

This is happening to me tonight, March 30, 2020.

I am also experiencing this issue today when I freshly installed 2.0.

I had to add a whitelist to cryptoprevent for GOG. If you check the eventviewer you'll see that it was blocking /programdata/gog.com/ files

#MeToo

I don't have cryptoprevent. I try the "netsh winsock reset" trick. And 6 sec after I log in, I lost connection and the software close after I click "Ok". It happens on my Windows 10 machine. I don't have this problem on my Mac.

I uninstall and reinstall GOG Galaxy, the problem persist. For the test, I disabled my Firewall.

Same here. On one pc gog galaxy will pop up "Connection to Communication Service was lost" after about 6-10 seconds from launch.
If I ignore the error I can use gog galaxy but it will not sync my saves. On another pc on the same network everything works normally.

I have a pihole installed on the network, but it's not filtering anything directed at gog.com

Just got this issue today, with a brand new install on a fresh Windows install (latest updates). Looks like for me, at least, it's a Windows 10 firewall issue. I added all the GOG executables I could find (including the ones in C:\ProgramData\GOG.com\Galaxy\redists) to my firewall and it seems to be working without throwing this error anymore. I'd just disable Windows 10 Firewall, but some part of XBox streaming to the PC requires it.

Just had this issue. Reset winsock and rebooted, seems to work now.

Hey, thanks a bunch!
I had a second account logged in on my Mac and had been having this issue.

When I logged out and left only one account active GoG Galaxy started to wrok!
Hope this fix works for others as well :)

Cheers!

In case anyone else encounters it in the same situation, I ran into this issue when running GOG Galaxy on a machine I'm connected to via remote desktop. As soon as I was on the machine locally, the error doesn't happen. Not sure why this matters, but something in Galaxy seems to be incapable of working over a remote desktop connection.