git submodule: update --remote --checkout + upstream branch change
- From
D. Ben Knoble <ben.knoble@gmail.com>
- Date
- Jan 20, 2026, 02:20 UTC
- Message-ID
- <CALnO6CCkcp-Pj-M6yCnr3O-DJE3PedEcqGah3e+E9C4Awqf+Kg@mail.gmail.com>
On my build of git.git origin/master (with ps/history merged in, but that shouldn't affect this), I received a confusing error today:
git submodule update --remote --checkout
…
Unable to find refs/remotes/origin/HEAD revision in submodule path
'…submod…'Turns out the upstream repository had renamed the main branch from master to main, and the git dir (.git/modules/…submod…/refs/remotes/origin) still had
ref: refs/remotes/origin/main
This is weird, because I could successfully "git fetch" inside the submodule, and "git ls-remote" showed HEAD on the remote pointing at the same place as refs/heads/main. In fact, I was so puzzled that I didn't understand where this error had come from (grepping in the source found builtin/submodule--helper.c; GIT_TRACE2=1 was not really any help here), nor did I have very high hopes of solving it except that I happened to know where to look for occurrences of "master" that might need changed.
A simple "git -C …submod… remote set-head origin -a" solves the problem; is there something the submodule code needs to do to handle this more gracefully, such as fixing it automatically or letting the user know what possible causes are? Or something I can do to avoid this coming up with other repositories I use as submodules?
-- D. Ben Knoble