fatal: Not a valid object name

Git’s fatal: Not a valid object name error means you referenced a commit, branch, tag, or other object that doesn’t exist in your repository’s object database.

What It Means

Git stores everything — commits, trees, blobs, tags — as objects identified by a SHA-1 hash (a 40-character hex string). When you run a command that requires a valid object reference (a branch name, commit hash, or tag), Git looks it up in its internal database. If it can’t find it, Git reports that the name isn’t a valid object.

Why It Happens

• You typed a commit hash incorrectly (missing characters, wrong branch).
• The branch name doesn’t exist yet (you haven’t made the first commit, or you misspelled the name).
• You’re referencing a commit from a different repo or a remote that hasn’t been fetched.
• The commit was garbage-collected or the repository is corrupted.
• You ran git checkout with a name that doesn’t match any branch, tag, or commit.

How to Fix It

1. Verify the reference exists

List all branches:

git branch -a

List all tags:

git tag

View recent commits with their full hashes:

git log --oneline -10

2. Check for the first commit

A common cause: you created a repo with git init but haven’t committed anything yet. Branches don’t exist until the first commit:

git status        # see if there are files to commit
git add .
git commit -m "Initial commit"

After the first commit, git branch will show main (or master).

3. Fetch remote branches

If the branch exists on the remote but not locally:

git fetch origin
git checkout <branch-name>

4. Use the full or partial commit hash

# Use enough of the hash to be unique (7+ characters)
git show abc1234

# Or the full 40-character hash
git show abc1234def5678...etc

5. Check for orphan branches

If you used git checkout --orphan <branch>, that branch has no commits. Make a commit first, then the branch name becomes a valid reference.