Using the slash character in Git branch name

Question

I'm pretty sure I saw somewhere in a popular Git project the branches had a pattern like "feature/xyz".

However when I try to create a branch with the slash character, I get an error:

$ git branch labs/feature
error: unable to resolve reference refs/heads/labs/feature: Not a directory
fatal: Failed to lock ref for update: Not a directory

Same problem for (my initial attempt):

$ git checkout -b labs/feature

How does one create a branch in Git with the slash character?

Hokanson

FWIW anything before the slash will generate a directory under .git/refs/heads ie if you do git checkout -b feature/123 then inside your projectRootFolder/.git/refs/heads directory you'll see a directory named: feature where inside that directory you'll see a branch named 123. Later if you create another feature/124 then inside the feature directory, you'll see a branch named 124 – Bonheur

Answer 1

Are you sure branch labs does not already exist (as in this thread)?

You can't have both a file, and a directory with the same name.

You're trying to get git to do basically this:

% cd .git/refs/heads
% ls -l
total 0
-rw-rw-r-- 1 jhe jhe 41 2009-11-14 23:51 labs
-rw-rw-r-- 1 jhe jhe 41 2009-11-14 23:51 master
% mkdir labs
mkdir: cannot create directory 'labs': File exists

You're getting the equivalent of the "cannot create directory" error.
When you have a branch with slashes in it, it gets stored as a directory hierarchy under .git/refs/heads.

---

Note that labs must not be an existing branch, as ddruganov points out in the comments:

 git switch -c 19023-commerce/19033-commerce-view 19023-commerce

 # Fails with:

 fatal: cannot lock ref 'refs/heads/19073-commerce-view/99999-test-branch': 
 'refs/heads/19073-commerce-view' exists; 
  cannot create 'refs/heads/19073-commerce-view/99999-test-branch'

As explained in "git push: refs/heads/my/subbranch exists, cannot create":

• If branch b exists, no branch named b/anything can be created.
• Likewise, if branch dev/b exists, dev/b/c cannot be created.

This is a git internal limitation.

Emeric

Thanks for the in depth reply.. Interstingly I tried git branch foo/bar (which worked); then git branch -d foo/bar, but I see that the foo/ directory (now empty) still exists! EDIT: and it is replaced as soon as I do "git branch foo". All is well. – Hokanson

@faB: wicked... but not unexpected: you deleted bar (in the 'foo' namespace), but not foo (which could serve as a namespace for other branch or be a branch itself) – Emeric

This doesn’t really matter, but git doesn’t change its stance even when you call pack-refs, so it’s going out of its way to protect you from this. – Industrial

To summarize the answer: You can have slashes in branch names. OP already had a labs branch and tried to create labs/feature, which git balked at. – Hultgren

@Hultgren so whats the solution? how do i specify that i branched from some specific reference branch? – Kamseen

@Kamseen Simply by making sure you don't have a file which is part of the branch you are trying to create. – Emeric

@Emeric in my case I didnt have any files with such names; im talking about branching from "foo" to "foo/bar" which apparently is not possible – Kamseen

@Kamseen What version of Git are you using, on which OS? What exact command did you type, and what was its output? – Emeric

@Emeric git 2.33, macos 11.5.1; git checkout -b 19023-commerce/19033-commerce-view; the output was the same as in this topic; the branch 19023-commerce already exists by the way – Kamseen

@Kamseen Try git switch -c 19023-commerce/19033-commerce-view 19023-commerce – Emeric

@Emeric doesnt work, same error message; 'refs/heads/19023-commerce' exists – Kamseen

Let us continue this discussion in chat. – Emeric

Answer 2

It is possible to have hierarchical branch names (branch names with slash). For example in my repository I have such branch(es). One caveat is that you can't have both branch 'foo' and branch 'foo/bar' in repository.

Your problem is not with creating branch with slash in name.

$ git branch foo/bar
error: unable to resolve reference refs/heads/labs/feature: Not a directory
fatal: Failed to lock ref for update: Not a directory

The above error message talks about 'labs/feature' branch, not 'foo/bar' (unless it is a mistake in copy'n'paste, i.e you edited parts of session). What is the result of git branch or git rev-parse --symbolic-full-name HEAD?

Dyson

Thanks, sorry about the confusion, I first wrote a foo/bar example, but paste error message from my actual test. Will not do it again :) And sorry also for my mistake, indeed I had a "labs" branch already. – Hokanson

Answer 3

I forgot that I had already an unused labs branch. Deleting it solved my problem:

git branch -d labs
git checkout -b labs/feature

Explanation:

Each name can only be a parent branch or a normal branch, not both. Thats why the branches labs and labs/feature can't exists both at the same time.

The reason: Branches are stored in the file system and there you also can't have a file labs and a directory labs at the same level.

Distraction

Exactly what I want! THANKS – Convert

Answer 4

Sometimes that problem occurs if you already have a branch with the base name.

I tried this:

git checkout -b features/aName origin/features/aName

Unfortunately, I already had a branch named features, and I got the exception of the question asker.

Removing the branch features resolved the problem, the above command worked.

Stingaree

Answer 5

Branch name is case sensitive and so if there are folders created in Azure by your release manager, folder names should match exactly. Learned it hard way raising it with manager.

Yelena

Answer 6

In case someone has this issue where they're not able to checkout to a branch for eg: features/23 because it says branch features exists, but you cannot find it on Github - it might be that you have a local branch named features which is causing it.

Delete the local branch with git branch -D features and then you should be able to checkout with git checkout features/23 and it should work as expected.

Ditmore

Answer 7

just had the same issue, but i could not find the conflicting branch anymore.

in my case the repo had and "foo" branch before, but not anymore and i tried to create and checkout "foo/bar" from remote. As i said "foo" did not exist anymore, but the issue persisted.

In the end, the branch "foo" was still in the .git/config file, after deleting it everything was alright :)

Mankind

Answer 8

I do this from Visual Studio Git Changes

As previously mentioned. I made the misstake of creating a dev branch. main dev

thinking that later I could just call them dev/somebranchname.

Solution was to delete dev and then create the dev/somebranchname. Next dev branch will be called dev/nextbranchname. This integrates very well with Visual Studio where dev becomes a folder view and the branches line up after that

Innerdirected