I am trying to connect my Gmail account to n8n Cloud using the Gmail Trigger and the default “Sign in with Google” flow, but I keep running into the same error and I am a bit stuck.
Every time I click “Sign in with Google”, Google immediately blocks the login with “Error 400: redirect_uri_mismatch”. There is no consent screen and no account selection, it fails instantly. This happens consistently across different browsers, in incognito mode, and even when using a completely different Google account.
To rule things out, I already tried pretty much everything on the Google side. I created and deleted Google Cloud projects, enabled the Gmail API, set up OAuth consent screens, checked redirect URIs, and also tested without using any custom OAuth at all. I also cleared cookies, logged out everywhere, tried Safari and Chrome, and tested incognito, but the behavior is always the same. As soon as I press “Sign in”, Google shows the mismatch error.
I am using n8n Cloud with my own subdomain and I am not self-hosting. From my understanding, the default n8n Cloud Gmail OAuth should just work without a custom Google project, which is why this is confusing. At this point it feels like either a cloud-side OAuth config issue or something specific to my n8n instance.
Has anyone run into this before on n8n Cloud, and is there anything else I can check or reset on my side that I might be missing?
