Recover from corrupted repository

[korrat]

The other day, I accidentally mounted my home drive under /tmp. Then systemd-tmpfiles went through and cleaned it up for me (deleted everything older than 10 days).

While I was able to recover most repositories from backups (a little outdated) or git forges, some local repos still have issues because they are missing some operations it seems.

Every time I run any jj command, I get the following error:

$ jj
Internal error: Failed to load an operation
Caused by:
1: Object 7a6a3401286ea861bb516697baa4cdaaf9cb3da5f0bbb3884ba96371ce486b4695b7e1cb6064702ffdc4459b530874ef8bdf50b72959b10471299c034ff5e100 of type operation not found
2: Cannot access /home/korrat/zettelkasten/.jj/repo/op_store/operations/7a6a3401286ea861bb516697baa4cdaaf9cb3da5f0bbb3884ba96371ce486b4695b7e1cb6064702ffdc4459b530874ef8bdf50b72959b10471299c034ff5e100
3: No such file or directory (os error 2)

I still have all files for the latest version of the repository. Is there any way to recover at least some of the history from the repository?

Or do I need to reset the repository to the latest recorded version (how?) and then commit the latest state in a single change?

[PhilipMetzger]

See the discussion in #4423.

[anka-213]

Regardless of what, start with making a full backup so you can recover if you messed something up

cp -a yourProject yourProject.bak

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If you're fine with losing all the jj-specific data, then the easiest option would be to (if not colocated, first extract the git-dir), then remove the .jj directory and run jj init again. Though, it will be somewhat tricky to recover any commits that are not on a branch. They are still there (git log --all --oneline --graph will show them), but there's nothing distinguishing old from current commits.

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But if you're lucky, then only the latest operation is broken. In that case, you can look at the latest few operations with

ls -t .jj/repo/op_store/operations | head

and check if one of them works with

jj op log --at-operation someOpHash

If so, you can recover by manually replacing the current op hash with one that's not broken

ls .jj/repo/op_heads/heads/
rm .jj/repo/op_heads/heads/*
touch .jj/repo/op_heads/heads/someOpHash

then you'll only lose the part of history that's newer than that operation.

[marco-m-pix4d]

@anka-213 this saved by bacon! I owe you a beer (or any beverage) !!!