Google Service Account Permission Error on HTTP Request

Questions
1

Hi everyone,

I’m encountering an authorization issue while trying to integrate n8n with Google Pub/Sub. Despite following the setup documentation and having a “Connection successful” status in n8n, I’m getting a permission error when trying to create a topic.

Error Message:

Forbidden - perhaps check your credentials?
User not authorized to perform this action.

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Here a simple workflow example

Current Google Service Account Setup:

  1. Created and configured a Service Account in Google Cloud Console
  2. Enabled the Pub/Sub API
  3. Granted the service account Pub/Sub Admin permissions
  4. Downloaded and imported the JSON key into n8n
  5. Configured the required OAuth scopes as per documentation: https://www.googleapis.com/auth/pubsub

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Here are my credentials configured and validated in my n8n credentials panel.

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I also setted the scopes how suggested on the docs:

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Any guidance on resolving this permission issue would be greatly appreciated. I’ve verified all the configurations multiple times but can’t identify what’s causing the authorization failure.

Information on your n8n setup

  • n8n version: 1.75.2
  • Database (default: SQLite): Postgres
  • Running n8n via (Docker, npm, n8n cloud, desktop app): Railway template
2

hi @Castanova

Welcome to the community! From the looks of it, seems that google is blocking that PUT request somehow. Which docs are you following?

top of mind, try to play around the configs on google’s side to enable/remove permissions.