I am trying to use GMAIL API in my RShiny app to send emails. I followed the steps and it worked for few emails but then it started showing me the following error:
Warning: Error in gmailr_POST: Gmail API error: 401 Request had invalid authentication credentials. Expected OAuth 2 access token, login cookie or other valid authentication credential. See https://developers.google.com/identity/sign-in/web/devconsole-project