git cannot open .git/FETCH_HEAD
error: cannot open .git/FETCH_HEAD: Permission denied
Was one of the first errors that ever happened to me.
Perhaps you already knew, but this is possibly happening because of not having permissions for changing/viewing that directory.
The idea is to change the permissions, perhaps use:
chmod
or
chown
I found further answers here Trying to git pull with error: cannot open .git/FETCH_HEAD: Permission denied.
if you are using ubuntu, use sudo key word before.
sudo git pull
if you are using windows, use administrator mode