[git] Error pushing to GitHub - insufficient permission for adding an object to repository database

In my case there were no unified authentication (e. g. within the domain + AD-like service) between my machine and git virtual server. Therefore git users and group are local for the virtual server. In my case my remote user (which I use to login into remote server) was just not added into remote git group.

ssh root@<remote_git_server>
usermod -G <remote_git_group> <your_remote_user>

After that check the permissions like it's described in the posts above...