remote: Invalid username or password. If you log in via a third party service you must ensure you have an account password set in your account profile. 17: fatal: Authentication failed

I’ve been experimenting with some Unity features, one of them is the Cloud Build. On my test game I have a submodule repo and, from the logs in the build server, I could see that the submodule was causing the build to fail.

After searching a little bit I found this post inside Unity Forum:

Ya submodules should work as long as you are using the git@ syntax (not git:// or https://) and you make sure that the ssh key generated by Cloud Build for you has access to both the main repository and the submodule.

So in my case, I already added the same SSH key to both repositories but I still had to change the .gitmodules file. So instead of:

https://[ACCOUNT]@bitbucket.org/[ACCOUNT]/[REPO_NAME].git

you do:

git@bitbucket.org:[ACCOUNT]/[REPO_NAME].git

After doing this I got my first build working!