Same problem. I have never had any Galaxy issues until now. I guess as long I can play via web installers, it's fine

Figured it out. CD Projeckt, your integration with 3rd party services is shit. Galaxy should not break just because you can't sync with EPIC. I'm removing sync. I don't even know why I enabled it.

I still can't log into my GOG account. I've had NO access to my account/games for close to 2 months now...

GOG's customer support is garbage. Their support ticket system doesn't even work.

Honestly, after being denied access to my account for this long I am no longer interested in supporting GOG. I'll never buy a game from GOG again or recommend them to anyone I know.

I had the same issue but it was resolved after uninstalling (I use a uninstaller so it removes all "not actually removed" files).

May I suggerst that you all make sure that after uninstalling this folders don't exist (and if they do, manually delete them):

C:\Program Files (x86)\GOG Galaxy
C:\Program Files\GOG Galaxy
C:\ProgramData\GOG.com\Galaxy
%localappdata%\GOG.com\Galaxy <-- This is the same as "C:\Users\<your username here>\AppData\Local\GOG.com\Galaxy"

Try reinstalling after that.

If that doesn't work:

My uninstaller also registers what a program adds to the registry while it's installing, so here's a list to all registry values that are created while it installs, so after uninstalling, execute Regedit with admin privileges (WARNING: Editing manually the registry is an advanced feature, you COULD break and brick your windows if you delete what you shouldn't) and make sure this keys/values are not there (and manually delete them if you must):

HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Run|Value|GogGalaxy
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Notifications\Data|Value|418A073AA3BC3475
HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\GOG.com\GalaxyClient\paths|Value|client
HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\GOG.com\GalaxyClient\paths
HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\GOG.com\GalaxyClient|Value|clientExecutable
HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\GOG.com\GalaxyClient|Value|version
HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\GOG.com\GalaxyClient
HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\Windows\CurrentVersion\Uninstall\{7258BA11-600C-430E-A759-27 E2C691A335}_is1|Value|DisplayIcon
HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\Windows\CurrentVersion\Uninstall\{7258BA11-600C-430E-A759-27 E2C691A335}_is1|Value|DisplayName
HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\Windows\CurrentVersion\Uninstall\{7258BA11-600C-430E-A759-27 E2C691A335}_is1|Value|EstimatedSize
HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\Windows\CurrentVersion\Uninstall\{7258BA11-600C-430E-A759-27 E2C691A335}_is1|Value|HelpLink
HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\Windows\CurrentVersion\Uninstall\{7258BA11-600C-430E-A759-27 E2C691A335}_is1|Value|Inno Setup: App Path
HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\Windows\CurrentVersion\Uninstall\{7258BA11-600C-430E-A759-27 E2C691A335}_is1|Value|Inno Setup: Deselected Tasks
HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\Windows\CurrentVersion\Uninstall\{7258BA11-600C-430E-A759-27 E2C691A335}_is1|Value|Inno Setup: Icon Group
HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\Windows\CurrentVersion\Uninstall\{7258BA11-600C-430E-A759-27 E2C691A335}_is1|Value|Inno Setup: Language
HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\Windows\CurrentVersion\Uninstall\{7258BA11-600C-430E-A759-27 E2C691A335}_is1|Value|Inno Setup: Selected Tasks
HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\Windows\CurrentVersion\Uninstall\{7258BA11-600C-430E-A759-27 E2C691A335}_is1|Value|Inno Setup: Setup Version
HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\Windows\CurrentVersion\Uninstall\{7258BA11-600C-430E-A759-27 E2C691A335}_is1|Value|Inno Setup: User
HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\Windows\CurrentVersion\Uninstall\{7258BA11-600C-430E-A759-27 E2C691A335}_is1|Value|InstallDate
HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\Windows\CurrentVersion\Uninstall\{7258BA11-600C-430E-A759-27 E2C691A335}_is1|Value|InstallLocation
HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\Windows\CurrentVersion\Uninstall\{7258BA11-600C-430E-A759-27 E2C691A335}_is1|Value|NoModify
HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\Windows\CurrentVersion\Uninstall\{7258BA11-600C-430E-A759-27 E2C691A335}_is1|Value|NoRepair
HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\Windows\CurrentVersion\Uninstall\{7258BA11-600C-430E-A759-27 E2C691A335}_is1|Value|Publisher
HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\Windows\CurrentVersion\Uninstall\{7258BA11-600C-430E-A759-27 E2C691A335}_is1|Value|QuietUninstallString
HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\Windows\CurrentVersion\Uninstall\{7258BA11-600C-430E-A759-27 E2C691A335}_is1|Value|UninstallString
HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\Windows\CurrentVersion\Uninstall\{7258BA11-600C-430E-A759-27 E2C691A335}_is1|Value|URLInfoAbout
HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\Windows\CurrentVersion\Uninstall\{7258BA11-600C-430E-A759-27 E2C691A335}_is1|Value|URLUpdateInfo
HKEY_LOCAL_MACHINE\Software\WOW6432Node\Microsoft\Windows\CurrentVersion\Uninstall\{7258BA11-600C-430E-A759-27 E2C691A335}_is1


Please note, this next registry entries have user-dependant addresses, so the "S-1-5-21-00000... etc" numbers will be different on your system, and the <username> part would be the usernames on your PC:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\bam\State\UserSettings\S-1-5-21-000000000-0000000000-00000000 00-1001|Value|\Device\HarddiskVolume3\Users\<username>\AppData\Local\Temp\GalaxyInstaller_RLxhr\GalaxyIn staller.exe
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\bam\State\UserSettings\S-1-5-21-000000000-0000000000-00000000 00-1001|Value|\Device\HarddiskVolume3\Users\<username>\AppData\Local\Temp\is-7AAVT.tmp\GalaxySetup.tmp
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\bam\State\UserSettings\S-1-5-21-000000000-0000000000-00000000 00-1001|Value|\Device\HarddiskVolume3\Windows\Temp\{4E9BFFAC-FE5A-4AC9-B26F-A96EC19284BD}\.cr\VC_redist.x64.ex e
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\bam\State\UserSettings\S-1-5-21-000000000-0000000000-00000000 00-1001|Value|\Device\HarddiskVolume3\Windows\Temp\{7C3A4E2F-F720-4985-9F39-55A6735E9A12}\.cr\VC_redist.x86.ex e
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\bam\State\UserSettings\S-1-5-21-000000000-0000000000-00000000 00-1008|Value|\Device\HarddiskVolume3\Program Files (x86)\GOG Galaxy\GalaxyClient.exe

I have seen a few topics on this forum on GOG Galaxy 2.0 faling to launch for a few people. I myself had a similar issue yesterday when I tried to log in and got the message "Oops, something went wrong, bla, bla...". Here is a link to a discussion on the forums about downgrading to a previous version of the Galaxy client - I have tried this apporach and it worked beautifully for me:

https://www.gog.com/forum/general_beta_gog_galaxy_2.0/how_to_keep_galaxy_v12_client_and_avoid_the_forced_v20_beta_update/page1

If you follow the instructions to the letter, you can get back to all of your games and not have to worry about the client crapping out on you.

This just happened to me i tried just reinstalling but it didn't work but what you said to manually delete folders it worked thanks

GOG Galaxy's been down for about 10 hours now.

Yup, still down, for the last few months it is always somethhing wrong with either GOG web site or Galaxy or both or the download speed is bad or Galaxy loses connection for a few minutes whil downloading a game every now and then.... quality dropped significantly

This result is one of the top in google when searching for cannot log into to GOG.com so adding my comment:
I had to change my DNS setting in my router, was using OpenDNS which apparently doesnt work well with anything gog.com related. Swapped to Cloudflare 1.1.1.1