public string ConvertToBase64(string text)
 {
     return Convert.ToBase64String(Encoding.UTF8.GetBytes(text))
     .Replace("+", "-")
     .Replace("/", "_")
     .Replace("=", "");
 }

 public async Task<ResponseResult> SendEmails(string reciepient_email, string GUID)
 {
     var client_id = _config["SMTP:client_id"];
     var client_secret = _config["SMTP:client_secret"];
     if (client_id == null || client_secret == null)
     {
         return new ResponseResult(false, "Unable to fetch token");
     }

     string[] scopes = { GmailService.Scope.GmailSend };
     var redirectURI = GoogleAuthConsts.LocalhostRedirectUri;

     

     var oauthCredentials = GoogleWebAuthorizationBroker.AuthorizeAsync(
         new ClientSecrets
         {
             ClientId = client_id,
             ClientSecret = client_secret
         }, scopes, "user", CancellationToken.None).Result;


     var access_token = await oauthCredentials.GetAccessTokenForRequestAsync();

     var gmail_access_token = GoogleCredential.FromAccessToken(access_token)
     .CreateScoped(GmailService.Scope.GmailSend);

     var gmailService = new GmailService(new BaseClientService.Initializer
     {
         HttpClientInitializer = gmail_access_token,
     });

     var emailMessage = new MimeMessage();
     emailMessage.From.Add(new MailboxAddress("",_config["SMTP:from"]));
     emailMessage.To.Add(new MailboxAddress("", reciepient_email));
     emailMessage.Subject = "Invite to Prescreening Test";
     emailMessage.Body = new TextPart(MimeKit.Text.TextFormat.Html) { Text= "WALLAHI LUIGI" };

     var gmailMessage = new Message
     {
         Raw = ConvertToBase64(emailMessage.ToString()),
     }; 
     var result = await gmailService.Users.Messages.Send(gmailMessage, "user").ExecuteAsync();
     
     return new ResponseResult(false, "Error with emailing service");
 }

I’m using the above code to try and send an email using the google gmail api using .net core 6

But i get a Error 400: redirect_uri_mismatch, with additional details of Request details: redirect_uri=http://127.0.0.1:49747/authorize/ flowName=GeneralOAuthFlow

https://i.sstatic.net/MIICCjpB.png
I’ve added these as the redirect uris in my oauth key (type web application)
Considering what other answers have recommended, I have added both http and https variants but it still doesn’t work

Any recommendations on how I should change my code to get this to work