Git Squash Rebase Error: Complete Fix Guide

The error “Cannot ‘squash’ without a previous commit” occurs when you try to squash the first commit in a sequence during interactive rebase, as there’s no prior commit to merge it into. You can recover by using git rebase --edit-todo to fix the commit list, then git rebase --continue, or abort with git rebase --abort and restart with proper squash ordering.

Contents

• Understanding the Squash Error
• Immediate Recovery Steps
• Fixing the Commit List
• Alternative Recovery Methods
• Preventing This Error
• Best Practices for Squashing

Understanding the Squash Error

The “Cannot ‘squash’ without a previous commit” error happens when you attempt to mark the first commit in your interactive rebase list as a squash operation source. As Bruno Scopelliti explains, “It can’t be squash, because squash modifies the commit before it.”

This typically occurs in two scenarios:

• When you’re trying to squash commits in a new repository with only a few commits
• When you include the very first commit of a branch in your squash operation

The error occurs because Git’s squash operation needs a “previous commit” to merge the current commit into. If you’re trying to squash commit A, there must be a commit B before it that commit A can be merged into.

Immediate Recovery Steps

When you’re stuck in this state, follow these immediate steps:

1. Check your current rebase status:

   bash

   git status
   

   You’ll likely see you’re in the middle of an interactive rebase.

2. Use the edit-todo command:
   As multiple sources confirm, the most reliable recovery method is:

   bash

   git rebase --edit-todo
   

   This command allows you to edit the rebase todo list without aborting the entire operation source.

3. Fix the commit list:
   Open the editor and ensure that:

   • No commit that’s the first in the sequence is marked as “squash”
   • At least one “pick” or “edit” command exists before any “squash” commands
   • The first commit is always “pick” or “edit”, never “squash”

Fixing the Commit List

When you run git rebase --edit-todo, you’ll see the interactive rebase todo file. Here’s how to fix it:

Common Mistakes to Fix

1. First commit marked as squash:

   # Wrong - first commit can't be squash
   squash abc1234 Commit message
   pick def5678 Another commit
   
   # Correct - first commit should be pick
   pick abc1234 Commit message
   squash def5678 Another commit
   

2. Empty or malformed todo list:
   If the file appears corrupted or empty, you may need to recreate it manually or abort and start over.

After Editing

Once you’ve fixed the commit list:

1. Save and close the editor
2. Run:
   bash

   git rebase --continue
   

   This will apply your corrected commit list and continue the rebase process source.

If That Doesn’t Work

If git rebase --continue still fails, you may need to:

1. Abort the current rebase:
   bash

   git rebase --abort
   

2. Start over with a corrected command:
   bash

   git rebase -i HEAD~3  # Adjust number as needed
   

Alternative Recovery Methods

Method 1: Complete Abort and Restart

If you’re having persistent issues with the interactive rebase:

1. Abort the rebase completely:

   bash

   git rebase --abort
   

   This will restore your repository to the state before the rebase attempt source.

2. Start fresh with correct parameters:

   • Use git rebase -i <base-commit> where <base-commit> is the hash of the first commit chronologically
   • Ensure the first commit in the list is always “pick”

Method 2: Manual Squash Without Rebase

If interactive rebase continues to cause problems:

1. Reset to the commit before the ones you want to squash:

   bash

   git reset --soft HEAD~2  # Adjust number based on commits to squash
   

2. Commit the changes manually:

   bash

   git commit -m "Combined commit message"
   

Method 3: Using --root Flag

For repositories where you want to squash commits starting from the very beginning:

git rebase -i --root

This gives you access to all commits, including the initial empty commit source.

Preventing This Error

Understanding Commit Order

Remember that in interactive rebase, commits are processed from oldest to newest. When you mark a commit as “squash”, it will be merged into the immediately preceding non-squashed commit source.

Best Practices

1. Always start with “pick”:
   The first commit in your interactive rebase list should always be “pick” or “edit”, never “squash”.

2. Use the right number of commits:
   If you want to squash 2 commits into 1, use git rebase -i HEAD~3 to include the target commit plus the 2 you want to squash.

3. Preview before applying:
   Consider using git rebase -i --autosquash for automatic squash ordering when appropriate.

Best Practices for Squashing

When to Squash

Squashing is most appropriate when:

• You have multiple small commits that logically belong together
• You’re cleaning up a feature branch before merging
• You want to create cleaner, more readable commit history

Safe Squashing Workflow

1. Always work on a branch:
   Never squash commits directly on main/master or other shared branches.

2. Test after each squash:
   After squashing, ensure your code still works by running tests and checking functionality.

3. Communicate with your team:
   If working on a shared repository, inform teammates about significant history changes.

Advanced Squashing Techniques

For more complex scenarios:

# Squash all commits since a specific point
git rebase -i <commit-hash>

# Squash commits but keep the original commit messages
git rebase -i --autosquash HEAD~5

Remember that once you’ve pushed commits to a shared repository, rebasing (including squashing) creates a new history that conflicts with the existing remote history. In such cases, you may need to force push with git push --force-with-lease.

Sources

1. Stack Overflow - “Cannot ‘squash’ without a previous commit” error while rebase
2. Reddit r/git - Using git rebase -i, gives me this error message
3. Bruno Scopelliti - Squash commits with git rebase
4. jdhao’s digital space - A Guide on Squashing Commits with git-rebase
5. DEV Community - Fix “cannot ‘squash’ without a previous commit” for Git
6. Stack Overflow - git rebase cannot ‘squash’ without a previous commit
7. Emacs Stack Exchange - magit - cannot ‘squash’ without a previous commit
8. Git Documentation - git-rebase
9. Stack Overflow - Recovering from a failed rebase
10. jvns.ca - git rebase: what can go wrong?

Conclusion

Recovering from the “Cannot ‘squash’ without a previous commit” error is straightforward once you understand the root cause. The key takeaways are:

1. Use git rebase --edit-todo to fix the commit list when you’re stuck in the middle of a failed rebase
2. Never mark the first commit as “squash” - it must be “pick” or “edit”
3. Abort with git rebase --abort if you need to start completely fresh
4. Plan your squash operations carefully by using the right number of commits and proper ordering

By following these recovery steps and understanding why the error occurs, you can successfully squash your commits and maintain a clean Git history. Remember to always work on feature branches when performing interactive rebases, and test your changes after completing the operation.