A few years back I created a small custom application for a client that utilized their Google logins for authentication. The web application was written with ASP.NET MVC and utilized Katana/Owin pipeline. The common practice to setup that application with Google sign in was to also enable the Google+ API. If you have done this then like me you have received an email recently that explains, as of March 2019 the Google+ API’s will be shut down. I have spent the last few days trying to read through the documentation to understand what needs to be done to fix this, without completely switching up the current login flow, however they don’t seem to make this transition easy for .NET applications. Thankfully I finally found the answer I was looking for, a workaround posted in GitHub comments, to address this exact issue. For those of you who are in the same boat as me have a look at this comment . I have made the changes recommended here and I can verify that my Google Sign-In is now working again without the Google+ API enabled.