How to fix CONFLICT (content): Merge conflict in file.txt error: could not apply abc1234... commit message in Git

When Git reports a conflict, first check which files need attention:

git status

Files listed under "Unmerged paths" or showing "both modified" need conflict resolution. You can also see the current failing patch:

git am --show-current-patch

Open each conflicted file in your editor. You'll see conflict markers like this:

<<<<<<< HEAD
// This is the code from the target branch (already rebased commits)
const result = calculateTotal(items);
=======
// This is the code from your commit being applied
const result = computeSum(items);
>>>>>>> abc1234 (commit message)

The section between <<<<<<< HEAD and ======= shows the target branch version.
The section between ======= and >>>>>>> shows your commit's version.

Important during rebase: "HEAD" refers to the rebased state so far, not your original branch. "Theirs" and "ours" are swapped compared to merge conflicts.

Edit each conflicted file to create the correct final version:

1. Remove all conflict markers (<<<<<<<, =======, >>>>>>>)
2. Keep the code you want (could be from either version or a combination)
3. Save the file

Example resolution:

// Final resolved version - combining both changes
const result = calculateTotal(items); // Kept the better function name

For simple cases, you can use Git's built-in tools:

# Keep your version (the commit being rebased)
git checkout --theirs path/to/file.txt

# Keep target branch version
git checkout --ours path/to/file.txt

Or use a visual merge tool:

git mergetool

After editing each conflicted file, stage it to mark as resolved:

git add path/to/file.txt

Or stage all resolved files at once:

git add -A

Verify all conflicts are resolved:

git status

There should be no files under "Unmerged paths".

Once all conflicts are resolved and staged, continue the rebase:

git rebase --continue

Git will apply the resolved commit and move to the next one. If more conflicts arise, repeat the resolution process.

If you get "No changes - did you forget to use 'git add'?": This means the resolved version is identical to the target branch. You can skip this commit:

git rebase --skip

If the conflicts are too complex or you want to start over, abort the rebase:

git rebase --abort

This returns your branch to its exact state before the rebase started. You can then:
- Try a different approach (merge instead of rebase)
- Break up your changes into smaller commits
- Coordinate with teammates about conflicting changes