These two files contains absolute submodule path:
{submodule}/.git
.git/modules/{submodule}/config
So, if you moved the repo, the absolute path in these two files are not valid, and cause the ‘not a git repository’ error. Just fix these files manually.
Update:
1.) Delete the relevant section from the .gitmodules file. You can use below command:
git config -f .gitmodules --remove-section "submodule.submodule_name"
2.) Stage the .gitmodules changes
git add .gitmodules
3.) Delete the relevant section from .git/config. You can use below command:
git submodule deinit -f "submodule_name"
4.) Remove the gitlink (no trailing slash):
git rm --cached path_to_submodule
5.) Cleanup the .git/modules:
rm -rf .git/modules/path_to_submodule
6.) Commit:
git commit -m "Removed submodule <name>"
7.) Delete the now untracked submodule files
rm -rf path_to_submodule