Backups. What a better time to test ’em than when you need ’em. Don’t lie. I know you’ve been there too. In an unfortunate turn of events, I had to restore a number of bare git repos from recent off-site copies (made with the handy rdiff-backup), but they needed a bit more work to be functional.

Once restored, I couldn’t pull or push from my existing working copies. I was greeted with cryptic error messages instead: fatal: git upload-pack: not our ref 0000000000000000000000000000000000000000 and ! [remote rejected] master -> master (missing necessary objects), respectively.

No amount of searching led to an adequate solution. So I simply leveraged git’s distributedness, and used one of the clone to recreate my bare repo. I was nonetheless a bit worried about having lost a few commits on the tip.

Playing in the bare repo later on led me to a more satisfying solution. Apparently, the refs/heads/master file was corrupted (empty), and editing it to contain the full sha-1 of the tip was enough to fix the issue. I found the sha-1 of the desired commit in the packed-refs file at the root of the bare repo. Once done, everything worked as before, and pre-existing working copies were able to pull and push without issue.

I learned two things:

• A bit more about git
• That I didn’t actually have any more commits there

Backups! Yay!

Cryptic error messages

working-copy$ git pull
fatal: git upload-pack: not our ref 0000000000000000000000000000000000000000
fatal: unable to write to remote: Broken pipe
working-copy$ git push

Enumerating objects: 98, done.
Counting objects: 100% (98/98), done.
Delta compression using up to 2 threads
Compressing objects: 100% (92/92), done.
Writing objects: 100% (92/92), 27.87 KiB | 951.00 KiB/s, done.
Total 92 (delta 62), reused 0 (delta 0), pack-reused 0
remote: fatal: bad object refs/heads/master
fatal: bad object refs/heads/master
To remote:bare-repo
 ! [remote rejected] master -> master (missing necessary objects)
error: failed to push some refs to 'remote:bare-repo'

Fixing the bare repo

bare-repo.git$ git log
fatal: your current branch appears to be broken
bare-repo.git$ cat HEAD
ref: refs/heads/master
bare-repo.git$ cat refs/heads/master
bare-repo.git$ cat packed-refs
# pack-refs with: peeled fully-peeled sorted 
8fe5cdc45f8b35044da5a431369bc313411fbfd4 refs/heads/install_rtm
fe7020ffe89e34f57d2f8d680e727e6ef03593b6 refs/heads/master
bare-repo.git$ echo fe7020ffe89e34f57d2f8d680e727e6ef03593b6 > refs/heads/master
bace-repo.git$ git log
# Now works!