OAuth Redirect URL stuck with `localhost` and consent windows complains on Error 400: redirect_uri_mismatch

[Zohar]

Disclaimer: I’ve seen several issues on this problem, but none resolved my problem.

When creating new Gmail OAuth credentials, the redirect URL is stuck on localhost. I can’t figure out why and where is this coming from.

Then on the consent window I am receiving this error Error 400: redirect_uri_mismatch :

I’m not sure the two are related, I only suspect they do.

FWIW, I used the external URL in Google:

I’m not so sure as to how to debug this issue.

My configuration:

• Running self-hosted in a Docker
• My .env:

N8N_RUNNERS_ENABLED=true
VUE_APP_URL_BASE_API=https://n8n.example.com/
# N8N_HOST=localhost
N8N_HOST=n8n.example.com
N8N_PORT=5678
N8N_PROTOCOL=https
N8N_EDITOR_BASE_URL=https://n8n.example.com/
N8N_DIAGNOSTICS_ENABLED=false

WEBHOOK_URL=https://n8n.example.com/
WEBHOOK_TUNNEL_URL=https://n8n.example.com/

Information on your n8n setup

• n8n version: 1.83.2
• Database (default: SQLite): Postgresql
• n8n EXECUTIONS_PROCESS setting (default: own, main): ??
• Running n8n via (Docker, npm, n8n cloud, desktop app): Docker
• Operating system: Raspberri Pi OS

[Zohar]

OK - Very strange. After reading this post I went back to Google API config and added the localhost redirection URL.

The immediate result was that the OAuth2 dialogue presented me with my Google accounts (!!!). However once I approved the permissions the process breaks because the browser is then trying to redirect to localhost and this obviously doesn’t work.

So I’m one step forward, but still no solution.

[hrishikesh]

With the variables you’ve setup, the redirect URI in n8n editor should match the domain you’ve setup. Are you sure the env vars are being read/applied?

[Zohar]

@hrishikesh I’m sure but then I may be wrong. How should I go on verify this?

[Zohar]

If I could use one of the nodes in order to run something like echo $ENV['N8N_HOST] or echo $N8N_HOST then I guess that would be decisive.
Can I ?

[hrishikesh]

That should be possible using the code node: process.env.N8N_HOST

[Zohar]

Thanks @hrishikesh. When using process I’m getting an error Cannot find name 'process'. Do you need to install type definitions for node? Try npm i --save-dev @types/node.

Same goes for using $env …

[Zohar]

Problem solved! I’m using n8n’s self hosted starter kit which uses docker-compose.
The variables I have in .env are not picked up by docker unless explicitly adding an -env_file directive to docker-compose.yml

I opened a PR just in case: Include .env in docker-compose.yml by zohar · Pull Request #43 · n8n-io/self-hosted-ai-starter-kit · GitHub

[Zohar]

Now it happens in form node…