git submodule update -> already exists and is not an empty directory

When typing this :
git submodule update

Having this error :
fatal: destination path 'xxx' already exists and is not an empty directory. 
fatal: clone of 'git@bitbucket.org:xxxxx/your-repo.git' into submodule path 'xxx' failed

Solution
git submodule deinit --force . 
git submodule init 
git submodule update --recursive