Git Fsck

git fsck (file system check) verifies the integrity of your Git repository's object database, identifying corrupted, missing, or dangling objects.

What Does git fsck Do?

git fsck walks through every object in the .git/objects directory and checks:

• Each object is readable and internally consistent.
• Every object referenced by another object actually exists.
• No SHA-1 checksums are corrupted.

It reports any problems it finds, including dangling commits, blobs, and trees.

Run a Basic Integrity Check

git fsck

Output on a healthy repository:

Checking object directories: 100% done.
Checking connectivity: done.

If problems exist, you'll see lines like:

dangling commit a3f6f1c9e29a3e82a4dcb3f59e8ab3d28a12c9af
dangling blob d1e8f91b45e8e1f9e4aa84b2e1830c4b5d674cd0

What Are Dangling Objects?

Dangling objects are Git objects that exist but aren't referenced by any branch, tag, or HEAD. They're usually the result of:

• Commits made in detached HEAD state that were abandoned.
• Branches that were deleted without being merged.
• Stashes that were dropped.

Dangling objects are not errors — they're just unreferenced. git gc will eventually remove them.

Recover a Dangling Commit

If you accidentally deleted a branch or dropped a stash, git fsck can help you find the commit:

git fsck --lost-found

Objects that can be recovered are written to .git/lost-found/. Inspect a recovered commit:

git show a3f6f1c

Create a branch from it to bring it back:

git checkout -b recovered-work a3f6f1c

Find Dangling Blobs (Lost File Contents)

git fsck --lost-found --unreachable

Lost blobs appear in .git/lost-found/other/. You can read each one:

cat .git/lost-found/other/d1e8f91b45e8e1f9e4

Check Connectivity Only

Skip full object validation and just check that all referenced objects exist:

git fsck --connectivity-only

tip

If your terminal unexpectedly closes during a Git operation, run git fsck afterwards to check for partial or corrupted objects. For most corruptions, restoring from a remote clone is the easiest fix.

Common Mistakes

Confusing dangling objects with corruption — dangling commits and blobs are normal and not errors. Real corruption shows as error: or broken link messages.

Not checking the remote after corruption — if a repository is corrupted locally, the cleanest fix is usually git clone from the remote rather than manually patching objects.

Ignoring git fsck output — if git fsck reports actual errors (not just dangling objects), investigate before the repository gets worse. Reach out to your team or check the remote backup.

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Next Steps: Understanding Gitflow and Branching Strategies