fatal: Need to specify how to reconcile divergent branches on git pull

Status: draft · Answer: draft · Ecosystem: git · Solutions: 1 · Article revision 5 by migration: Keep one answer per environment; earlier overlapping approaches moved to alternatives. · history · Last verified: not recorded · License: CC0-1.0

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Symptom

git pull refuses to run and exits 128 with fatal: Need to specify how to reconcile divergent branches., preceded by a hint block listing pull.rebase false, pull.rebase true and pull.ff only. Nothing is merged or rebased and the working tree is unchanged. It usually appears right after git push was rejected with ! [rejected] main -> main (fetch first).

Context

git 2.55.0 on macOS or Linux (behavior introduced in 2.27), local repo with one unpushed commit, remote advanced by another clone, and neither pull.rebase nor pull.ff configured. Also hit by CI scripts that assumed git pull would simply merge.

Root cause

Since 2.27 git refuses to guess the strategy for a diverging pull. With both pull.rebase and pull.ff unset and the two histories diverged, it stops and demands an explicit policy. This is a policy gate, not a merge conflict: the histories combine fine once a strategy is named. The rescue is to name the strategy, in config or on the command line.

Solutions

1. git pull --rebase: replay local commits on top of the remote (pull-rebase) · 0.30 success · n=1 · low confidence · rev 1

Applies to: Unpushed local commits that nobody else has based work on · Environment: git · macos · linux

git pull --rebase
Confirm the result is linear: git log --oneline --graph shows your commits on top of the remote ones, git rev-list --merges --count HEAD is 0.
Make it the repo default if that is the team's convention: git config pull.rebase true.

Verify:

t=$(mktemp -d); cd "$t" && git init -q --bare -b main o.git && git clone -q o.git a && cd a && git config user.email a@x && git config user.name a && printf b > s.txt && git add . && git commit -qm base && git push -q -u origin main && cd "$t" && git clone -q o.git b && cd b && git config user.email b@x && git config user.name b && printf r > r.txt && git add . && git commit -qm remote && git push -q origin main && cd "$t/a" && printf l > l.txt && git add . && git commit -qm local && git pull -q --rebase && test "$(git rev-list --merges --count HEAD)" = 0 && git log --oneline | grep -q local

Expected: exit code 0 and a linear history containing both commits

Notes: Rewrites the hashes of your local commits. Safe while they are unpushed; if they are already on a shared branch, rebase is the wrong tool.

Lint diagnostics: verify_target_not_in_fix, requires_network, creates_files, requires_repo

Outcomes

solution	environment	success	solved	failed	n	confidence
all	global	0.36	3	1	4	ok · 2026-10-17
pull-rebase	global	0.30	1	0	1	low · 2026-10-17
pull-rebase	macos-26 + git-2.55	0.30	1	0	1	low · 2026-10-17

Failed attempts — 4 ruled-out approaches

Kept for reference: the answer above supersedes them, and they are hidden by default. Do not retry them unless your environment differs. Machine reads fetch them with ?include=archived_failures.

git pull --ff-only in the same state — exits 128 with fatal: Not possible to fast-forward, aborting.; a fast-forward is impossible by construction once both sides have commits.
git config pull.ff only as a 'safe default' — only hides the prompt while histories have not actually diverged; afterwards every diverged pull dies with the fast-forward fatal instead.
git push --force to get past the rejected push — it succeeds and deletes the other clone's commit from the remote without warning its author. This is exactly the outcome the pull gate exists to prevent.
git reset --hard origin/main — discards the local commits that caused the divergence; they survive only in the reflog for a while.

Alternatives (reference only)

These approaches were replaced by the answer above. They are kept for context and are not recommended.

git pull --no-rebase: keep both histories with a merge commit (pull-merge · Shared branches where rewriting local commits would break other clones)
Answer the question once, in config (set-policy · Any repo you own that keeps hitting the prompt) — The check has to run inside a repo, so it creates a throwaway one; git config alone exits 128 with 'fatal: not in a git directory'. Setting it globally changes every repository on the machine, including ones whose maintainers expect merge commits.

Boundaries

If both sides changed the same lines, git pull --rebase stops mid-rebase with Could not apply <sha> and leaves the repo in a detached rebase state; resolve and git rebase --continue, or git rebase --abort to return to the pre-pull state.
Rebasing rewrites local commit hashes; do not use it on commits that are already pushed to a shared branch.
pull.rebase set globally changes every repo on the machine, including ones where merge commits are expected.

Provenance

Not recorded.

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