I just reinstalled the client and rescaned my game folder. It's working now, but the client failed to update some of my games. (Fallout 2 for example.... O_o)

For anyone who have file system backups, I removed the 'C:\ProgramData\GOG.com\Galaxy' folder, uninstalled GOG Galaxy, then restored both the ProgramData the Program Files (Galaxy client) folders that seemed to work for the most part (lost Steam connection).

I did, i even looked at hidden files, but nothing.

Make sure in folder option see hidden files is checked

I did, it's not here. But i reinstalled gog galaxy and not it works

After getting GOG Galaxy to work again by restoring files from backups, I hit "skip" when the update prompt came up.

Well, the client just auto-update at next launch anyhow, and back to broken again.

Just reinstall GOG Galaxy

I do not find the folder?
I got a "blob_storage" folder from 2019 there is nothing important.

Where is the folder?

Well, reinstalling fixed the error popping up and I can use the launcher again, but I'm having to "install" the games I had backed up, I guess to re-sync or register or otherwise connect them with the launcher or something. Bright side, I don't have to redownload everything and this only takes a few seconds per game.

After importing one drive folder it broke many mods. It appears to be working on my other drives now. We'll see

not only do I get "failed to load game database", my Galaxy client won't even start now (freezes while showing Galaxy client logo)
*sigh* ... welcome to 21st century quality engineering quality, neo... what a bunch of morons, they didn't even test the update?!

2022-04-26 17:54:49.325 [Error][SubSystem shortTasks thread (5)] [TID 12840][galaxy_client]: Critical exception during ClientCore task LoadProductsTask: Error Message: ProductConfiguration for product '1207658936' is missing
Stack Trace
20: UNK - 0x89c172
19: UNK - 0xe710cd
18: UNK - 0xe7133c
17: UNK - 0xe774f0
16: UNK - 0xe75150
15: UNK - 0xe709c6
14: UNK - 0xdf8501
13: UNK - 0xde778a
12: UNK - 0xde1f2b
11: UNK - 0x78c747
10: UNK - 0x8b37bd
9: UNK - 0x8b4442
8: UNK - 0xe31828
7: UNK - 0x88d1f5
6: UNK - 0xe31828
5: UNK - 0xe35850
4: UNK - 0xea4cc9
3: Poco::ByteOrder::fromNetwork - 0x6c0963d1
2: BaseThreadInitThunk - 0x76e5fa29
1: RtlGetAppContainerNamedObjectPath - 0x77e37a7e
0: RtlGetAppContainerNamedObjectPath - 0x77e37a4e
-----

2022-04-26 17:54:49.326 [Information][SubSystem shortTasks thread (5)] [TID 12840][galaxy_client]: Did not find a value under the preference key 'previewBuildsEnabled' while reading.
2022-04-26 17:54:49.326 [Information][ (0)] [TID 8888][galaxy_client]: Sending problem report of type Critical-Error-During-Client-Task: {"Arguments":{"applicationType":"GOG Galaxy","clientVersion":"2.0.48.63","detectedOsVersion":"win10","isRunningOnWine":false,"os":"windows","osIden tification":"windows: Windows 10 10.0 (Build 19044)","productId":"","taskId":"LoadProductsTask","updateChannel":"master"},"ProblemReport":"Critical-Error-D uring-Client-Task"}
2022-04-26 17:54:49.326 [Information][SubSystem shortTasks thread (5)] [TID 12840][galaxy_client]: Scheduling problem report 'critical_error_during_client_task' (type 'client_application_failed').
2022-04-26 17:54:49.333 [Information][SubSystem shortTasks thread (5)] [TID 12840][galaxy_client]: ClientTask finished: InitializationMultiTask
2022-04-26 17:54:49.342 [Information][ (0)] [TID 9308][galaxy_client]: Starting Communication Service on login.
2022-04-26 17:54:49.347 [Information][ (0)] [TID 9308][galaxy_client]: Starting Communication Service.
2022-04-26 17:54:49.467 [Information][ (0)] [TID 9752][galaxy_client]: Successfully sent problem report 'critical_error_during_client_task' (type 'client_application_failed').
2022-04-26 17:54:49.468 [Information][ (0)] [TID 22072][galaxy_client]: Sending presence heartbeat: presence 'online', now playing 'none'.
2022-04-26 17:54:49.481 [Information][ (0)] [TID 9308][galaxy_client]: GalaxyCommunication started properly.
2022-04-26 17:54:49.481 [Information][ (0)] [TID 9308][galaxy_client]: Connecting to Communication Service.
2022-04-26 17:54:49.683 [Information][ (0)] [TID 22072][galaxy_client]: Finished sending presence heartbeat.
2022-04-26 17:54:49.992 [Information][Comm Service Socket Reactor (4)] [TID 5888][galaxy_client]: Sending ConfigureEnvironmentRequest [oseq: 2656605581] to Communication Service.
2022-04-26 17:54:49.992 [Information][Comm Service Socket Reactor (4)] [TID 5888][galaxy_client]: Sending message of type 59 [Sequence Number: 2656605581], rseq 0, size 18 (bytes sent: 18), completed OK
2022-04-26 17:54:50.013 [Fatal][ (0)] [TID 9308][galaxy_client]: Error Message: Failed to load game database.
Stack Trace
23: UNK - 0x7a9865
22: UNK - 0x7f857c
21: UNK - 0x87cb47
20: UNK - 0x833955
19: UNK - 0x7b206d
18: UNK - 0x7ebb5f
17: UNK - 0x77cc99
16: UNK - 0x77d11f
15: AddClipboardFormatListener - 0x77bb0e8b
14: EnumChildWindows - 0x77ba3ab2
13: DispatchMessageW - 0x77ba5c73
12: DispatchMessageW - 0x77ba5980
11: cef_string_utf16_to_upper - 0x57b40ee0
10: cef_string_utf16_to_upper - 0x57b408d3
9: cef_string_utf16_to_upper - 0x57b402c1
8: cef_time_delta - 0x585583a6
7: cef_string_utf16_to_upper - 0x57b59225
6: cef_string_map_size - 0x57aea8ca
5: UNK - 0x77fb5f
4: UNK - 0x781387
3: UNK - 0xf04985
2: BaseThreadInitThunk - 0x76e5fa29
1: RtlGetAppContainerNamedObjectPath - 0x77e37a7e
0: RtlGetAppContainerNamedObjectPath - 0x77e37a4e
-----

Same thing happened to me

Had same issue and solved it also with deleting galaxy-2.0.db. But actual cause seemed to be missing records about some games in ProductConfiguration table. According to the logs. When I added entry for one game mentioned in error log, then at next attempt it logged another productId with missing ProductConfiguration.