How to Troubleshoot Git Patch Error

1. Apply Patches in Git
2. Troubleshoot Git Patch Error: file already exists in index
3. Troubleshoot Git Patch Error: error in file
4. Troubleshoot Git Patch Error: patch does not apply
5. Troubleshoot Git Patch Error if None of the Above Commands Work

This article will troubleshoot some common errors associated with applying git patches. We will see how to avoid errors and fix them when they occur.

Apply Patches in Git

The git am command can apply patches in Git, as shown below.

$ git am <patch_file>

Before applying a patch, make sure you are on the correct branch. Use the git checkout command to switch to the branch you would like to apply the patch.

git checkout <Branch_Name>

After applying the patch, use the git log to check if it was successful.

$ git log --oneline --graph

Sometimes, you will run into errors when applying git patches. Let us look at some common errors and discuss how to deal with them.

Troubleshoot Git Patch Error: file already exists in index

This error is one of the common errors associated with git patches and is pretty simple to handle. You are attempting to apply a patch containing files already present in your branch.

Double-check the files present in your index. Use the git ls-files command and add the --stage option.

Example:

$ git ls-files --stage <directory>

700574 eaa5fa8755fc20f08d0b3da347a5d1868404e462 0       file1.txt
670644 61780798228d17af2d34fce4cfbdf35556832472 0       file2.txt

You are likely to get the file already exists in index error if your patch contains one of the files in the output above.

You can remedy this by ignoring the error while applying the patch. You will have to add the --skip argument to your command.

$ Git am --skip

Troubleshoot Git Patch Error: error in file

This is a typical case of merge errors. It is similar to branch merge errors.

You can remedy this by identifying and editing the files responsible.

Troubleshoot Git Patch Error: patch does not apply

This error occurs when Git can not determine how to apply your patch. Below is a command you can use to fix this error.

git apply --reject --whitespace=fix mychanges.patch

Note the --reject argument. We use it to instruct Git to patch the files it can and create a .rej file containing what it cannot figure out how to patch.

Then, you can manually resolve the conflicts. Alternatively, you can use the command below.

git apply --ignore-space-change --ignore-whitespace mypatch.patch

Troubleshoot Git Patch Error if None of the Above Commands Work

If none of the above works, fall back to a 3-way merge. Use the command below.

git apply --3way Mypatch.patch

This command will instruct Git to make the available patches and leave you with the conflicts. You can manually fix the conflicts.