On the website https://code.google.com/apis/console I have registered my application, set up generated Client ID: and Client Secret to my a
I had two request URIs in the Console, http://xxxxx/client/api/spreadsheet/authredirect and http://localhost.
I tried all the top responses to this question and confirmed that none of them were my problem.
I removed localhost from the Console, updated my client_secret.json in my project, and the mismatch error went away.