--no-cache causes "Data decryption failed, MAC check failed"

[pezcode]

I set up a repo and can run backups on it successfully, but noticed that deleting the rustic cache (C:\Users\xx\AppData\Local\rustic) breaks all operations on that repo. Same thing with --no-cache.

What might cause this? And can I fix this somehow? I ran repair index, but the error remains.

Any help appreciated 🙇

Here's the output for rustic check --no-cache:

[INFO] rustic v0.11.0
[INFO] command: ["C:\\Users\\xx\\scoop\\apps\\rustic\\current\\rustic.exe", "-P", "diskstation", "check", "--no-cache", "--log-level", "debug"]
[INFO] using config .\diskstation.toml
[INFO] using config .\common.toml
[INFO] repository local://XX/YY/rustic: password is correct.
[INFO] using no cache
[00:00:00] getting snapshots...           ████████████████████████████████████████         30/30
error: `rustic_core` experienced an error related to `cryptographic operations`.

Message:
Data decryption failed, MAC check failed.

For more information, see: https://rustic.cli.rs/docs/errors/C001


Some additional details ...

Context:
- nonce: [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]

Caused by:
aead::Error

(stacktrace omitted, it's just lots of <unknown>)

[pezcode]

Tried a few random things, and rustic prune seems to have fixed it. Does that rewrite/restore the remote repo index?

It's a little scary being able to brick a repo, so I'd really love to understand what caused this and how to prevent it 🙇 I only really used backup a dozen times or so, some of which were interrupted by Ctrl+C which I assume to be supported. No other fancy commands

[aawsome]

Hi @pezcode This seemed to be a snapshot file containing only of zero bytes. I am not sure how this can happen, most likely by an aborted backup, but it may also depend on the backend you are using.

In any case, if you (or some rustic command) remove that file and the check afterwards is fine, your repository is in a sane state.

[pezcode]

Thanks, that's good to know. For manual removal, it would help if rustic printed the offending snapshot file.

[aawsome]

Should be fixed in rustic-rs/rustic_core#482

[pezcode]

Amazing, thanks 😌