git Reference Error

You may encounter the following error messages when running a git push from a CI platform, such as Circle CI, Travis CI, Jenkins and others:

error: Could not read COMMIT_HASH
fatal: revision walk setup failed
fatal: reference is not a tree: COMMIT_HASH
! [remote rejected] master -> master (missing necessary objects)
! [remote rejected] master -> master (shallow update not allowed)

(Where COMMIT_HASH is a long hexadecimal number)

Cause

These errors are all caused by pushing from a shallow clone.

Shallow clones are often used by CI platforms to make builds faster, but you can’t push from a shallow clone to another git repository, which is why this fails when you try pushing to Aptible.

Resolution

To solve this problem, update your build script to run this command before pushing to Aptible:

git fetch --unshallow || true

If your CI platform uses an old version of git, --unshallow may not be available. In that case, you can try fetching a number of commits large enough to fetch all commits through to the repository root, thus unshallowing your repository:

git fetch --depth=1000000