Fix a Git detached head?

Question

I was doing some work in my repository and noticed a file had local changes. I didn\'t want them anymore so I deleted the file, thinking I can just checkout a fresh copy. I

Answer 1

Being in "detached head" means that HEAD refers to a specific unnamed commit (as opposite to a named branch) (cf: https://git-scm.com/docs/git-checkout section Detached head)

To fix the problem, you only need to select the branch that was selected before by

git checkout @{-1}

Answer 2

Here's what I just did after I realized I was on a detached head and had already made some changes.

I committed the changes.

$ git commit -m "..."
[detached HEAD 1fe56ad] ...

I remembered the hash (1fe56ad) of the commit. Then I checked out the branch I should have been on.

$ git checkout master
Switched to branch 'master'

Finally I applied the changes of the commit to the branch.

$ git cherry-pick 1fe56ad
[master 0b05f1e] ...

I think this is a bit easier than creating a temporary branch.

Answer 3

Detached head means you have not checked out your branch properly or you have just checked out a single commit.

If you encounter such an issue then first stash your local changes so that you won't lose your changes.

After that... checkout your desired branch using the command:

Let's say you want branch MyOriginalBranch:

git checkout -b someName origin/MyOriginalBranch

Answer 4

This approach will potentially discard part of the commit history, but it is easier in case the merge of the old master branch and the current status is tricky, or you simply do not mind losing part of the commit history.

To simply keep things as currently are, without merging, turning the current detached HEAD into the master branch:

1. Manually back up the repository, in case things go unexpectedly wrong.
2. Commit the last changes you would like to keep.
3. Create a temporary branch (let's name it detached-head) that will contain the files in their current status:

git checkout -b detached-head

4. (a) Delete the master branch if you do not need to keep it

git branch -D master

4. (b) OR rename if you want to keep it

git branch -M master old-master

5. Rename the temporary branch as the new master branch

git branch -M detached-head master

Credit: adapted from this Medium article by Gary Lai.

Answer 5

To further clarify @Philippe Gerber's answer, here it is:

Before cherry-pick, a git checkout master is necessary in this case. Furthermore, it is only needed with a commit in detached head.

Answer 6

Realizing I had a detached head without knowing how I managed to get it (like three commits away), I also found out that trying to merge, rebase or cherry-pick triggered hundreds of merge-conflicts, so I took a different approach:

1. (Assuming everything is committed (working tree is "clean"))

2. Save my commit messages: git log > /tmp/log

3. Save my working tree: mkdir /tmp/backup && cp -a all_my files_and_directories /tmp/backup

4. Revert to master: git checkout master

5. Remove all the working files and directories: rm ...

6. Use the backup: cp -a /tmp/backup/. .

7. git add and git commit using messages from saved /tmp/log, maybe repeating it with different sub-sets of files...

The disadvantage is that you loose your commit history if one file was changed multiple times since master, but in the end I had a clean master.