【Git】「failed to push some refs to」エラーの原因と対処法｜8パターン診断と個別対策完全ガイド

$ git push origin main
To github.com:user/repo.git
 ! [rejected]        main -> main (non-fast-forward)
error: failed to push some refs to 'github.com:user/repo.git'
hint: Updates were rejected because the tip of your current branch is behind
hint: its remote counterpart. ...

To github.com:user/repo.git                             ← pushの対象
 ! [rejected]        main -> main (non-fast-forward)   ← 本当の原因はここ
error: failed to push some refs to 'github.com:user/repo.git'   ← 外側サマリー
hint: Updates were rejected because the tip of your current ... ← ヒント

# STEP 1: 失敗したpushを再実行して全文を取得
git push 2>&1 | tee /tmp/push-error.log

# STEP 2: "rejected" 行の括弧内キーワードを確認
grep -E "rejected|error|hint|remote" /tmp/push-error.log

# STEP 3: リモートとローカルの関係を把握
git fetch origin
git log --oneline --graph --all --decorate -20

# STEP 4: ahead/behind 件数を確認
git rev-list --left-right --count origin/main...HEAD
# 出力: "3    2"  ← リモートが3件先行、ローカルが2件固有

 ! [rejected]        main -> main (non-fast-forward)
error: failed to push some refs to '...'
hint: Updates were rejected because the tip of your current branch is behind
hint: its remote counterpart.

# リモートの変更を取り込んで履歴を整理
git pull --rebase origin main

# コンフリクトが出たら解消
git add .
git rebase --continue

# 改めてpush
git push origin main

git@github.com: Permission denied (publickey).
fatal: Could not read from remote repository.
error: failed to push some refs to '...'

# SSH疎通確認
ssh -T git@github.com

# HTTPS形式ならトークン再発行
git remote set-url origin https://TOKEN@github.com/USER/REPO.git
# または credential.helper を設定
git config --global credential.helper store

remote: error: GH006: Protected branch update failed for refs/heads/main.
remote: error: Required status check "ci/build" is expected.
 ! [remote rejected] main -> main (protected branch hook declined)
error: failed to push some refs to '...'

remote: pre-receive hook declined
 ! [remote rejected] main -> main (pre-receive hook declined)
error: failed to push some refs to '...'

# より親切なフックだと理由も表示される
remote: Error: commit message must start with Conventional Commits prefix

# メッセージを修正（直前のcommit）
git commit --amend -m "feat: 適切なprefix付きメッセージ"

# Signed-off-by 追加
git commit --amend --signoff --no-edit

# 巨大ファイルをLFSへ
git lfs track "*.psd"
git add .gitattributes

remote: error: File data/model.bin is 245.00 MB; this exceeds GitHub's file size limit of 100.00 MB
 ! [remote rejected] main -> main (pre-receive hook declined)
error: failed to push some refs to '...'

# Git LFSをインストール
git lfs install

# 対象パターンをLFS管理に
git lfs track "*.bin" "*.psd" "*.mp4"
git add .gitattributes

# 既存履歴から巨大ファイルを除く（git filter-repo）
pip install git-filter-repo
git filter-repo --strip-blobs-bigger-than 50M

# 改めてLFS化してcommit → push
git add data/model.bin
git commit -m "feat: model.bin をLFSで管理"
git push

# 共通祖先の有無を診断
git merge-base HEAD origin/main

# unrelatedならマージで統合
git pull origin main --allow-unrelated-histories
git push

# shallow状態を確認
git rev-parse --is-shallow-repository
# true なら shallow

# 完全履歴に戻す
git fetch --unshallow

# すべてのリモートを深めたい場合
git fetch --all --unshallow

# 改めてpush
git push origin main

 ! [rejected]        v1.0.0 -> v1.0.0 (already exists)
error: failed to push some refs to '...'
hint: Updates were rejected because the tag already exists in the remote.

# 同じタグをどうしても上書きしたい場合
git push --force origin v1.0.0

# ただしタグの上書きは通常禁忌
# 新しいバージョン番号にする方が無難
git tag v1.0.1
git push origin v1.0.1

# 全タグを一度にpush
git push origin --tags

git push
# → (non-fast-forward)

git fetch origin
git log --oneline origin/main..HEAD
# ローカル固有コミット
git log --oneline HEAD..origin/main
# リモート固有コミット

git pull --rebase origin main
git push

# 直接mainにpushしてreject
git push origin main
# → (protected branch hook declined)

# 直前のコミットを新ブランチに移動
git switch -c feature/from-main
git push -u origin feature/from-main

# main を取り消し
git switch main
git reset --hard origin/main   # ローカル側のmainをリモートに合わせる

# PRでレビュー → マージ

# エラー確認
git push
# remote: error: File data/video.mp4 is 120.00 MB; exceeds 100MB

# LFSセットアップ
git lfs install
git lfs track "*.mp4"
git add .gitattributes

# 既に履歴に入ってしまった場合は filter-repo で除去
git filter-repo --path data/video.mp4 --invert-paths

# LFS経由で再追加
cp /backup/video.mp4 data/video.mp4
git add data/video.mp4
git commit -m "feat: video.mp4 をLFS管理で追加"
git push

git push -u origin main
# → rejected (fetch first)

git pull origin main --allow-unrelated-histories
# コンフリクト解消
git push -u origin main

# pullでrebaseを自動適用
git config --global pull.rebase true

# 新ブランチ初回pushで自動upstream設定
git config --global push.autoSetupRemote true

# force pushは force-with-lease を既定に
git config --global alias.fp 'push --force-with-lease'

# pre-commitフレームワーク
pip install pre-commit
pre-commit install