Switching to a branch with submodules is not possible

[enumag]

The problem

The issue has been reported 3 years ago in #13016 and mistakenly closed as duplicate of #9174 while it is in fact a separate and still existing bug.

If GitHub Desktop cloned a repository on a branch without submodules, when attempting to switch to a branch with submodules, GitHub Desktop throws the following error:

fatal: not a git repository: ../.git/modules/<submodule name>
fatal: could not reset submodule index

Release version

3.6.1

Operating system

Windows 11

Steps to reproduce the behavior

1. Create a repository with a default branch set to a branch without any submodules.
2. Create a branch in the repository and add a submodule to it.
3. Switch back to the default branch without submodule.
4. Checkout this repository with GitHub Desktop. It should checkout the default branch without submodules.
5. Try checking out the submodule branch. GitHub Desktop should throw the error mentioned at the top of this page.

Log files

Can't share them publicly because I noticed it on a private repository. It should be easy to reproduce though.

Screenshots

Additional context

No response

[steveward]

Thanks for opening this @enumag.

[steveward]

Closing this as a duplicate of #18673.