Advanced Timemachine not working (Catalina)

[SirSlarti]

Hi folks,
since a while timemachine is not working. I have done the basic troubleshooting, but somewhere is a problem.
The error message is could not create local snapshot to back up from.
When I listed with

# tmutil listlocalsnapshotdates /
Snapshot dates for volume group containing disk /:
2021-09-05-125947
2021-09-05-135945
2021-09-05-145941
2021-09-05-155941
2021-09-05-165804
2021-09-05-175941

But I cannot find them on /

# ls -la
drwxrwxr-x   9 root  wheel   288 Sep  6 12:58 .
drwxr-xr-x  23 root  wheel   736 Aug 18 16:50 ..
drwxrwxr-x  17 root  admin   646 Feb  9  2021 BOOT
drwxrwxr-x   8 root  wheel   340 Sep  6 12:35 HoG_External
drwxrwxr-x  30 root  admin  1088 Sep  4 19:23 Mac OS 2TB
drwxrwxrwx  46 root  admin  1632 Sep  4 18:21 Mac OS 4TB
lrwxr-xr-x   1 root  wheel     1 Sep  6 12:12 MacOS_0521 -> /

Anyhow I deleted them with

# tmutil deletelocalsnapshots /
Deleted 26 Time Machine local snapshots for volume group containing disk '/'

com.apple.TimeMachine.2021-09-05-125947.local
com.apple.TimeMachine.2021-09-05-135945.local
com.apple.TimeMachine.2021-09-05-145941.local
com.apple.TimeMachine.2021-09-05-155941.local
com.apple.TimeMachine.2021-09-05-165804.local
com.apple.TimeMachine.2021-09-05-175941.local

I suspect a rights error? I should have enough space, as well did mostly exclusions for troubleshooting to make sure I have space.

Any ideas, please?
Thanks.

 

[appltech]

Hi! Out of this list, which is your external drive you're trying to backup to : Hog external, Mac OS 2 or 4 tb?
Also, is your external drive formatted properly? Were you able to back up before?

 

[SirSlarti]

Hi! Out of this list, which is your external drive you're trying to backup to : Hog external, Mac OS 2 or 4 tb?
Also, is your external drive formatted properly? Were you able to back up before?

- No matter what drive!
- It worked before on any drive! - what format is recommended?
- Yes.

 

[appltech]

- No matter what drive!
- It worked before on any drive! - what format is recommended?
- Yes.

- "No matter what drive!" - ok, this is interesting. is there some data on those drives right now?
- "It worked before on any drive! - what format is recommended?" - Time Machine formats your drive or partition before the very first backup (and removes all files on that destination). It's either" macos extended journaled" on older OS versions or "apfs" on Big Sur. You may have "encrypted" next to them if "encypt backups" was selected while setting up your Time Machine drive. Encrypted drives have to be unlocked first to get access to backup contents
- if you suspect issues with file/folder access, check your external drives through "control+click -> get info"

let me know if any of these helped)