Essentially my issue is described here:
I have regenerated my github api keys from the netlify control panel at https://app.netlify.com/sites/mysite/settings/identity#services multiple times and am still getting this error response when I click ‘Login with Netlify Identity’ from my CMS page:
GET: https://mysite.netlify.com/.netlify/git/github/branches/master?ts=1562846613232 404 Not Found
The response is from github’s api and seems to indicate that my branch was not found:
documentation_url: "https://developer.github.com/v3/repos/branches/#get-branch" message: "Not Found"
The relevant portion of my config.yml is:
backend: name: git-gateway branch: master
It might be worth noting that the github repo I am working with belongs to an Organization, of which I am a fully-privileged member and is private. It was not deployed using the one-click deploy. Rather it is a next.js site and was deployed following the instructions here: https://www.netlifycms.org/docs/nextjs/
Again, I have tried multiple times with re-generating the github API keys to no avail, which leads me to suspect that this is a different issue.