Ambiguous Error on Restore

[kanjieater]

I'm trying to restore from a backup. I got error code 104 which I can't seem to find anyone else dealing with.

[2025-08-15 00:05:09,669] INFO: etc/borgmatic.d/an.yml
[2025-08-15 00:05:09,669] INFO: borgmatic/bootstrap
[2025-08-15 00:05:09,669] INFO: borgmatic/bootstrap/manifest.json
[2025-08-15 00:05:09,671] INFO: rcs: [104]
[2025-08-15 00:05:09,671] INFO: terminating with warning status, rc 104
[2025-08-15 00:05:09,703] ERROR: Treating exit code 104 as an error, as per configuration

I'm uncertain if I have lost data or not. But I configured my backup to stop so I could investigate. I'm also unsure of which file is the problematic one. Any help on why this could happen, what it means, and how to prevent would be helpful.

So far I've pieced together:

BackupOSError rc: 104
{}: {}

So i dug through the code:

class BackupIO:
    op = ""

    def __call__(self, op=""):
        self.op = op
        return self

    def __enter__(self):
        pass

    def __exit__(self, exc_type, exc_val, exc_tb):
        if exc_type and issubclass(exc_type, OSError):
            E_MAP = {
                errno.EPERM: BackupPermissionError,
                errno.EISDIR: BackupPermissionError,
                errno.EACCES: BackupPermissionError,
                errno.EBUSY: BackupPermissionError,
                errno.ENOENT: BackupFileNotFoundError,
                errno.EIO: BackupIOError,
            }
            e_cls = E_MAP.get(exc_val.errno, BackupOSError)
            raise e_cls(self.op, exc_val) from exc_val

And i'm still not clear what issue is affecting me or why.

[ThomasWaldmann]

That log is not from borg (but from borgmatic), and it does not contain sufficient information to help you.

When using borg directly, you can give the --list option to list files and I guess even without that, it should output usable information in case of errors and warnings.

[ThomasWaldmann]

@witten ^

[witten]

Borg's exit code 104 is indeed a BackupOSError, but I'm also not sure why you're getting that in this case. Can we see your full log (redacted as necessary)? Is the log fragment you posting from running an extract or is it from a create? And what is the full command-line you're running?

[kanjieater]

It's an extract that I'm getting it on. Seems my original create log for this archive wasn't captured correctly (I made an issue on borgmatic issue tracker for that separately). I can try to post the full log soon. I'm waiting to run list as well until the repo unlocks as I'm trying to extract what stopped after this warning.

[kanjieater]

Borg's exit code 104 is indeed a BackupOSError, but I'm also not sure why you're getting that in this case. Can we see your full log (redacted as necessary)? Is the log fragment you posting from running an extract or is it from a create? And what is the full command-line you're running?

Here are the logs.
https://pastebin.com/UGss0wTa

The borg command is included in it: borg extract --lock-wait 60 --debug --list --show-rc /mnt/buan/bu/an-backup.borg::personalcontent-an-2025-08-11_12h28m

borgmatic --config /etc/borgmatic.d/an.yml extract --archive latest --destination /mnt/buph

The reason I posted to the borg was because I thought to Thomas's point that this wasn't clear what the issue was upon extraction from borg. But I still have not gotten a chance to run --list given the repo has been locked due to #8996

[ThomasWaldmann]

pastebin: again, this is not a borg log.

stuff i noticed:

• [2025-08-14 09:25:01,247] CRITICAL: /mnt/buan/bu/an-backup.borg: [Errno 2] No such file or directory: '/mnt/bumt/extract'

• System Volume Information and $RECYCLE.BIN: not sure if you are supposed to back up and restore these files, maybe rather not?

[witten]

Thanks for posting your logs. I don't see any obvious cause of the 104 exit code, but I second @ThomasWaldmann's recommendation of trying to run Borg directly. The Borg command that borgmatic looks to be running is someting like:

cd /mnt/buph
BORG_EXIT_CODES=modern borg extract --lock-wait 60 --debug --list --show-rc /mnt/buan/bu/an-backup.borg::personalcontent-an-2025-08-11_12h28m

You'll likely have to enter your passphrase manually when prompted.

[kanjieater]

Thank you. I had already started it like this:
sudo env BORG_PASSPHRASE=$(cat /mnt/srv/borgmatic/config/passphrase) borg extract --list --progress /mnt/buan/bu/an-backup.borg::shke-an-2025-08-11_12h28m > ~/code/bu/extract2.log 2>&1

I have 9 instances of this (no other errno's present)
[Errno 36] File name too long

104 never appeared in my raw borg extract log when i went to extract it this time. There are no other error codes. I would share my log, but I don't have a good way to scrub all the sensitive file names. I thought this would give some more information, but unfortuantely I'm not seeing anything new, just a list of 30k~ files and those handful of errno.

[ThomasWaldmann]

Well, that is an OSError, so borg extract's default behavior will be to emit a warning, skip the problematic file(s) and continue processing the remaining files.

So, likely the directory you are extracting into plus the length of extracted paths is more than your OS is supporting.

So you could try extracting to a a shorter base path.

Another means is to use --strip-components NUMBER to strip some leading path components from the extracted paths.

[kanjieater]

The file names are indeed excessively long. I was already aware of them. Am I am correct in understanding that rc 104 could have been caused by errno 36, and if there were other issues they would have shown here with other errno codes?

[ThomasWaldmann]

Yes, OSError when accessing backup files -> BackupOSError.

If you only have BackupOSErrors, the rc will be 104.

If there are different kinds of non-fatal errors, the rc will be a more generic 1 (IIRC).

[ThomasWaldmann]

@witten Guess the main issue here is that "[Errno 36] File name too long" was hidden from the user.

Could borgmatic invoke borg in a way so that warning output of borg gets shown to the user?

[witten]

Could borgmatic invoke borg in a way so that warning output of borg gets shown to the user?

It should. @kanjieater Is it possible that output was interspersed among other logs? You can also try increasing the verbosity to see if that makes a difference.

If the borgmatic ticket you've filed covers this issue, then we can continue the discussion there.

[ThomasWaldmann]

Guess there is nothing to do in borg.