I can't checkout a specific branch, "detached HEAD state"

Question

Me and my friend has a repo which he created. He then created a branch called "lexer" for us to work on.

The problem is that while he can switch forth and back between master and lexer it does not work at all for me.

Eventually I just started over (rm -rf repo and then cloned the repo) but it's still impossible to checkout the lexer branch?

On a freshly cloned repo:

git branch gives:

$ git branch
* master

git checkout lexer gives:

$ git checkout lexer
$ git status
On branch master
Your branch is up-to-date with 'origin/master'.

I CAN checkout origin/lexer but I end up in a detached HEAD state?

$ git checkout origin/lexer master
Note: checking out 'origin/lexer'.

You are in 'detached HEAD' state. You can look around, make experimental
changes and commit them, and you can discard any commits you make in this
state without impacting any branches by performing another checkout.

It is possible for me to push to the lexer branch by doing

git push origin HEAD:lexer

but well, I really would like to sort this mess out. It's so weird that it works for him but not for me? He says that he hasn't got any local changes from the git repo either...

Anyone have any clue?

score 67 · Accepted Answer · answered Feb 13 '16 at 18:34

67

I'm going to venture a guess that you have a directory named lexer at the top level. Since git checkout is used both to switch branches and to reset files in the tree, it's probably detecting that you don't have a branch called lexer but you do have a path and selects the second mode. It works for your friend because he already has a lexer branch.

Easiest workaround is probably to create the branch using git branch instead.

git branch --track lexer origin/lexer

should do that for you. You can then use git checkout to switch to it.

Another option might be to use the -- flag to git checkout. I haven't tried it but I think it should work:

git checkout lexer --

When you add --, the word before it is always considered a branch/commit/tree and the word after a path.

answered Feb 13 '16 at 18:34

Per Johansson

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1

The first workaround also works if there is a branch and a tag with the same name. – mjobrien Jul 14 '17 at 14:48
1

This worked for me, but I still don't know where the conflict was. I created a brand new branch to preserve my current changes, pushed to my remote, rm -rf'd everything. Recloned, fetched, checked out my recently-created branch via `git checkout origin/recently-created-branch` and boom, detached HEAD. Your first suggestion fixed everything for me immediately. – Shadoninja Oct 16 '17 at 17:50
I've been wondering what `--` does in git commands for like.... a year now. Thanks! – GrayedFox Jul 17 '18 at 13:15
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I've run into this -- without a conflicting directory of the same name. The second command would allow the checkout, but still with detached HEAD. The first (to add tracking info) is the right answer. Another useful variant: `git checkout -t origin/lexer`. Thanks! – geipel Apr 16 '19 at 21:04
git branch --track lexer origin/lexer works for me – Yang Wang Apr 04 '20 at 01:18

score 24 · Answer 2 · answered Oct 17 '18 at 16:11

24

Your probably want this:

git checkout -t origin/lexer

From git manual:

As a convenience, --track without -b implies branch creation...

and

-t, --track... When creating a new branch, set up "upstream" configuration... If no -b option is given, the name of the new branch will be derived from the remote-tracking branch

answered Oct 17 '18 at 16:11

Denis Pshenov

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This always works, if you used it first time on new repo else it will display message fatal: A branch named ...... etc – TheExorcist Feb 11 '20 at 13:21
Yessssssssss! *1e6 – scrat.squirrel Oct 09 '20 at 15:16

Phil H · Answer 3 · 2020-05-14T10:53:34.243

22

TLDR: This could just be a syntax issue. Instead of

git checkout origin/mybranch

Try:

git checkout mybranch

The steps git takes, given the following command:

git checkout origin/mybranch

git looks for a branch called 'origin/mybranch' in the local repo.
Not finding it, it will then look for a branch called 'origin/mybranch' in the available remotes.
Not finding that either, it tries treating that as a commit tag, and finds the tag 'origin/mybranch' against a specific commit. It checks out that commit for you, in a detached state.

But that wasn't what you wanted! You wanted the branch called 'mybranch'. If there's only one remote with such a branch (and nothing locally to confuse matters) then git will assume you meant this usage, filling in <remote> for you:

git checkout -b <branch> --track <remote>/<branch>

If it can't find a branch with the matching name, it defaults to this:

git checkout [--detach] <commit>

Which is where the detached HEAD message comes in.

See the git checkout docs, and pay careful note of <branch> vs <remote>.

edited May 14 '20 at 10:53

answered May 14 '20 at 10:44

Phil H

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this was my issue – JobHunter69 Aug 17 '20 at 16:31
this took me foreever to figure out – LuXxenatorX Sep 23 '20 at 10:41
this was my issues had to remove remotes/origin – SSS Nov 03 '20 at 19:12
Thank you Phil for the detail answer explaining the root cause. You have addressed the missing concept behind. Great. – Ahmed Sep 07 '22 at 02:17

Philippe · Answer 4 · 2018-06-15T10:08:13.667

14

You can't checkout lexer because you don't have the branch in your local repository (and surely a folder with the same name) . You only have the remote branch 'origin/lexer'. First you have to create the local branch :

git checkout -b lexer origin/lexer

A good explaination on the subject: https://git-scm.com/book/en/v2/Git-Branching-Remote-Branches#Tracking-Branches

edited Jun 15 '18 at 10:08

answered Feb 13 '16 at 18:38

Philippe

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This answer is just plain wrong - with current versions of git, checking out a non-existing local branch with corresponding branch name on (the only) remote will create and checkout a local version of that branch by default. See https://git-scm.com/docs/git-checkout: "If is not found but there does exist a tracking branch in exactly one remote (call it ) with a matching name..." – eis Apr 04 '17 at 06:29
Indeed, that's git default behavior but perhaps you missed the text `(and surely a folder with the same name)` that change this behaviour and which is the main problem here. And you could see that the accepted answer say exactly the same thing (but more completely). So, no, I don't think my answer was **plain** wrong... – Philippe Apr 05 '17 at 05:58
"You can't checkout lexer because you don't have the branch in your local repository[...] First you have to [..]" is the 'plain wrong' part. Yes, the folder seems to have been the issue, the other parts of this answer are not related. – eis Apr 05 '17 at 08:04

score 4 · Answer 5 · answered Feb 13 '16 at 18:41

You get into a detached HEAD state because origin/lexer is a remote tracking branch, and thus read only. You want to just checkout lexer, and do your work on that. Then, when you push, origin/lexer will be brought up to date.

Edit: Rereading your question, I see that you have tried to checkout lexer, but end up staying on master. It is strange that git checkout is failing silently. Try git checkout -t origin/lexer.

score 2 · Answer 6 · edited May 03 '18 at 16:10

2

Another wild guess: you are having a tag with identical name so

git checkout lexer

actually checks out the tag, not the branch

edited May 03 '18 at 16:10

Christian

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answered Apr 04 '17 at 06:25

Steliyan Georgiev

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This was my problem. Thanks! – Parker Kemp Jan 12 '22 at 19:16

score 1 · Answer 7 · edited May 23 '17 at 11:33

When you do: git checkout origin/lexer master you simply change your HEAD to point to the latest commit in our remote branch. It's a read only branch.

If you wish to understand what HEAD is read this :
How to move HEAD back to a previous location? (Detached head)

In your case you simply need to do the following:

Update your repository with the latest code with all branches and tags

# Update your local repository with all the remote branches
# --prune = remove all deleted data locally which was removed on the remote
git fetch --all --prune

Now you should have the latest branches locally.

Delete the old local branch

!!! IMPORTANT:
If you made modification and did not push them don't delete the local branch

git branch -D lexer

Checkout the desired branch

# don't use the remote simply the branch name
git checkout lexer

Now you have local branch with the name lexer checked out from your remote branch

score 0 · Answer 8 · answered Apr 26 '22 at 04:20

0

what I found that if that a branch doesn't exists or we made some mistake in branch name like feature/ or origin/ etc then I got detached head. check branch name properly then can do checkout branchname

answered Apr 26 '22 at 04:20

asifaftab87

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score -1 · Answer 9 · edited Dec 30 '20 at 13:07

-1

I just replace the command

$ git checkout v4.9.0

with

$ *git checkout -b v4.9.0

and it is working for me.

edited Dec 30 '20 at 13:07

Donald Duck

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answered Dec 30 '20 at 09:48

JRV

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`-b` option just creates a new branch. After creating the new branch code needs to be pulled from the remote branch – Gautham M Dec 30 '20 at 10:12

I can't checkout a specific branch, "detached HEAD state"

9 Answers9

Update your repository with the latest code with all branches and tags

Delete the old local branch

Checkout the desired branch

Linked

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