OpenID faced the problem of an underdefined spec, causing every OpenID provider to do things just different enough for them to not be portable with one another.

OpenID faced the problem of an underdefined spec, causing every OpenID provider to do things just different enough for them to not be portable with one another. Which is why OID withered away in favor of just implementing the biggest social media login used by your audience (Google, Microsoft, Twitter, Facebook and if your audience includes gamers, Steam) and relying on that instead.