git workflow_error ai_generated true

You need to start by 'git bisect start' — bisect session not initialized or in bad state

ID: git/bisect-bad-revision

Also available as: JSON · Markdown
90%Fix Rate
88%Confidence
45Evidence
2018-01-01First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
2 active — — —

Root Cause

Git bisect errors occur when the bisect session isn't properly initialized, bad/good commits are specified incorrectly, or the session state becomes corrupted. The three-step flow (start -> mark bad -> mark good -> test) must be followed precisely, and forgetting to reset after completion leaves the repo in a detached HEAD state.

generic

Workarounds

  1. 95% success Follow the correct bisect workflow: start, bad, good, test, repeat, reset 
    1) 'git bisect start' 2) 'git bisect bad' (current commit is bad) 3) 'git bisect good <known-good-commit>' 4) Test the code at the checkout point 5) 'git bisect good' or 'git bisect bad' based on test 6) Repeat until git identifies the first bad commit 7) 'git bisect reset' to return to your branch.

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

  2. 88% success Use git bisect run for automated bisection 
    Run 'git bisect run <test-script>' where the script exits 0 for good commits and non-zero for bad. Example: 'git bisect run python -m pytest tests/test_feature.py'. Git automatically checks out commits and runs your test until the first bad commit is found.

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

  3. 82% success Use git bisect skip for untestable commits 
    When a checkout can't be tested (build broken, unrelated failure), use 'git bisect skip' instead of good/bad. Git will try nearby commits. You can also skip ranges: 'git bisect skip <start>..<end>'.

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

Dead Ends

Common approaches that don't work:

  1. Running git bisect good/bad without first running git bisect start 95% fail

    Git bisect requires an active session. Running 'git bisect good' or 'git bisect bad' without 'git bisect start' first results in 'You need to start by git bisect start'. The session must be explicitly initialized.

  2. Forgetting to run git bisect reset after finding the culprit commit 70% fail

    After bisect completes, your repo is left in a detached HEAD state at the culprit commit. If you start making changes or committing without running 'git bisect reset' first, you'll be working on a detached HEAD and may lose work. Always run 'git bisect reset' to return to your original branch.

  3. Marking a commit as both good and bad, or swapping good/bad labels 85% fail

    If you accidentally mark a good commit as bad (or vice versa), bisect will converge on the wrong commit. Git cannot detect this mistake. The result will be a false positive. If the bisect result seems wrong, 'git bisect log' shows your markings for review.

Error Chain

Leads to: