Issue with adding common code as git submodule: "already exists in the index"

Question

I'm afraid there's not enough information in your question to be certain about what's going on, since you haven't replied to my follow-up question, but this may be of help in any case.

That error means that projectfolder is already staged ("already exists in the index"). To find out what's going on here, try to list everything in the index under that folder with:

git ls-files --stage projectfolder

The first column of that output will tell you what type of object is in the index at projectfolder. (These look like Unix filemodes, but have special meanings in git.)

I suspect that you will see something like:

160000 d00cf29f23627fc54eb992dde6a79112677cd86c 0   projectfolder

(i.e. a line beginning with 160000), in which case the repository in projectfolder has already been added as a "gitlink". If it doesn't appear in the output of git submodule, and you want to re-add it as a submodule, you can do:

git rm --cached projectfolder

... to unstage it, and then:

git submodule add url_to_repo projectfolder

... to add the repository as a submodule.

However, it's also possible that you will see many blobs listed (with file modes 100644 and 100755), which would suggest to me that you didn't properly unstage the files in projectfolder before copying the new repository into place. If that's the case, you can do the following to unstage all of those files:

git rm -r --cached projectfolder

... and then add the submodule with:

git submodule add url_to_repo projectfolder

You need to remove your submodule git repository (projectfolder in this case) first for git path.

rm -rf projectfolder

git rm -r projectfolder

and then add submodule

git submodule add <git_submodule_repository> projectfolder

Removing submodule manually involves number of steps and this worked for me.

Assuming you are in the project root directory and sample git module name is "c3-pro-ios-framework"

Remove the files associated to the submodule

rm -rf .git/modules/c3-pro-ios-framework/

Remove any references to submodule in config

vim .git/config

Remove .gitmodules

rm -rf .gitmodules

Remove it from the cache without the "git"

git rm --cached c3-pro-ios-framework

Add submodule

git submodule add https://github.com/chb/c3-pro-ios-framework.git

I had the same problem and after hours of looking found the answer.

The error I was getting was a little different: <path> already exists and is not a valid git repo (and added here for SEO value)

The solution is to NOT create the directory that will house the submodule. The directory will be created as part of the git submodule add command.

Also, the argument is expected to be relative to the parent-repo root, not your working directory, so watch out for that.

Solution for the example above:

1. It IS okay to have your parent repo already cloned.
2. Make sure the common_code directory does not exist.
3. cd Repo
4. git submodule add git://url_to_repo projectfolder/common_code/ (Note the required trailing slash.)
5. Sanity restored.

I hope this helps someone, as there is very little information to be found elsewhere about this.

if there exists a folder named x under git control, you want add a same name submodule , you should delete folder x and commit it first.

Updated by @ujjwal-singh:

Committing is not needed, staging suffices.. git add / git rm -r

Just to clarify in human language what the error is trying to tell you:

You cannot create a repository in this folder which already tracked in the main repository.

For example: You have a theme folder called AwesomeTheme that's a dedicated repository, you try do dump it directly into your main repository like git submodule add sites/themes and you get this "AwesomeTheme" index already exists.

You just need to make sure there isn't already a sites/themes/AwesomeTheme in the main repository's version tracking so the submodule can be created there.

So to fix, in your main repository if you have an empty sites/theme/AwesomeTheme directory then remove it. If you have already made commits with the sites/theme/AwesomeTheme directory in your main repository you need to purge all history of it with a command like this:

git filter-branch --index-filter \
              'git rm -r --cached --ignore-unmatch sites/theme/AwesomeTheme'     HEAD

Now you can run git submodule add [email protected] sites/themes/AwesomeTheme

Since the main repository has never seen anything (a.k.a index'd) in sites/themes/AwesomeTheme before, it can now create it.

I got it working by doing it the other way around. Starting with an empty repo, adding the submodule in a new folder called "projectfolder/common_code". After that it was possible to add the project code in projectfolder. The details are shown below.

In an empty repo type:

git submodule add url_to_repo projectfolder/common_code

That will create the desired folder structure:

repo
|-- projectfolder
    |-- common_code

It is now possible to add more submodules, and the project code can be added to projectfolder.

I can't yet say why it worked this way around and not the other.