Gmail send email is not working with the error saying - Error 400: redirect_uri_mismatch

[Arun1]

Describe the problem/error/question

I am using the gmail send send a message flow. I have selected Credential to connect → From the drop box, selected Create New Credential. Then I have created client id and secret key and pressed ‘Sign In with Google’ where the error saying Error 400: redirect_uri_mismatch

Here I am have redirect url as http://localhost:5678/rest/oauth2-credential/callback which I copied for later use.

But when I create the credential in https://console.cloud.google.com/ in the redirect URL box I was unable to give this redirect url because I am not using the localhost

My n8n workflow launched from oracle cloud free tier Ubuntu system. I have the public IP address from which I am running the n8n, but the same public IP address if I give in google console → redirect URL it is not accepting and it is asking for the domain name. I have copied the Fully qualified domain name from the oracle cloud and successfully created the Cliend ID and Secret Key.

So, I have configured Fully qualified domain name (not the ip addresss) in the google console, but in the n8n it is showing the redirect url as localhost like http://localhost:5678/rest/oauth2-credential/callback,

Hence when I press the ‘SignIn with Google’ the Error 400 is showing.

Not sure where / how to fix this redirect issue.

What is the error message (if any)?

Please share your workflow

(Select the nodes on your canvas and use the keyboard shortcuts CMD+C/CTRL+C and CMD+V/CTRL+V to copy and paste the workflow.)

Share the output returned by the last node

Information on your n8n setup

• n8n version:
• Database (default: SQLite):
• n8n EXECUTIONS_PROCESS setting (default: own, main):
• Running n8n via (Docker, npm, n8n cloud, desktop app):
• Operating system:

[Wouter_Nigrini]

Hi @Arun1,

Make sure to set the following environment variables as well when you self host n8n to make sure the redirect url displays correctly:

WEBHOOK_URL=https://whatever-your-oracle-host-url-is
N8N_HOST=whatever-your-oracle-host-url-is      ## Without the leading https://
N8N_PORT=5678
N8N_PROTOCOL=https
N8N_SECURE_COOKIE=true

Not sure how you are hosting, but if using docker, it’s just in the config. Restart your instance and see if it displays correctly.

Additional Notes:

1. You must have a dns record when setting the redirect url in google. Raw IPs will not work
2. You must have SSL setup for HTTPS