git clone_error ai_generated true

fatal: shallow file has changed since we read it

ID: git/shallow-clone-limitation

Also available as: JSON · Markdown
91%Fix Rate
89%Confidence
55Evidence
2023-06-01First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
2 active — — —

Root Cause

Shallow clones (depth=1) lack full commit history, breaking operations that require ancestry information like git log, git blame, git merge-base, and certain merge strategies. The shallow boundary file can also become stale during concurrent fetches.

generic

Workarounds

  1. 95% success Convert shallow clone to full clone with git fetch --unshallow 
    Run 'git fetch --unshallow' to download the complete commit history. This converts the shallow clone into a full clone. After this, all git operations (log, blame, merge-base, rebase) work correctly. In CI, add this step before any operation that requires history.

    Sources: https://git-scm.com/docs/git-fetch#Documentation/git-fetch.txt---unshallow

  2. 85% success Fetch a specific depth sufficient for the required operation 
    Run 'git fetch --depth=N' where N is large enough to include the commits you need (e.g., depth=100 for recent blame, depth=500 for a merge-base within the last year). Check with 'git rev-list --count HEAD' to confirm you have enough history.

    Sources: https://git-scm.com/docs/git-fetch

  3. 92% success Use blobless clone (--filter=blob:none) instead of shallow clone 
    Clone with 'git clone --filter=blob:none <repo-url>'. This downloads all commits and trees but fetches file contents (blobs) on demand. You get full commit history for log, blame, and merge-base, while still saving significant bandwidth and disk space on initial clone.

    Sources: https://git-scm.com/docs/partial-clone

Dead Ends

Common approaches that don't work:

  1. Expecting full git log or git blame output to work correctly with --depth=1 clone 92% fail

    A shallow clone with depth=1 only has the tip commit. git log shows a single commit, git blame cannot trace line origins beyond the shallow boundary, and any tool depending on full history produces incomplete or misleading results. This is by design, not a bug.

  2. Running git merge-base to find common ancestors in a shallow clone 88% fail

    merge-base requires reachable common ancestors between branches. In a shallow clone the commit graph is truncated, so merge-base either fails with a fatal error or returns incorrect results. This breaks rebase workflows and merge conflict resolution that depend on accurate base detection.

  3. Repeatedly fetching with small incremental depth increases to avoid downloading full history 70% fail

    Each git fetch --depth=N fetches from the tip, not from the current shallow boundary. Incrementally increasing depth is unreliable for reaching specific commits and can trigger 'shallow file has changed' race conditions when done concurrently. The total data transferred often exceeds a single --unshallow operation.

Error Chain

Leads to:
Frequently confused with: