HighLevel OAuth2 API Connection Failing - Token Exchange Error on oauth.n8n.cloud/oauth2/callback

Questions
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1

Hi all,

I’m experiencing a persistent issue with the HighLevel OAuth2 API credential connection in my n8n Cloud workflow. The OAuth authorization succeeds on GoHighLevel’s side, but the token exchange fails on n8n’s oauth callback endpoint.

Issue Details:

  • n8n Instance: Cloud (fabioprofityai.app.n8n.cloud)

  • Workflow ID: hvy0PO8mtgE-CJ5yW26qj

  • Workflow Name: “Book Appointment in GHL”

  • Credential Type: HighLevel OAuth2 API

  • Error: “Something went wrong. Please try again!” displayed on oauth.n8n.cloud/oauth2/callback

What’s Working:

  1. GoHighLevel successfully authorizes the OAuth request

  2. GoHighLevel generates an authorization code (e.g., code=9dd713320b08aa3c37747722dce848afde15f1f7)

  3. GoHighLevel correctly redirects to: https://oauth.n8n.cloud/oauth2/callback with the code and state parameters

  4. I can successfully complete the full authorization flow on GoHighLevel’s side, including:

    • Reviewing and approving permissions (Contacts, Calendars, Locations, Conversations)

    • Selecting the location/account to authorize

What’s Failing:
The n8n OAuth callback endpoint (oauth.n8n.cloud/oauth2/callback) fails to exchange the authorization code for an access token and displays the generic error message “Something went wrong. Please try again!”

Configuration Details:

HighLevel OAuth2 Credential Settings:

  • Authorization URL: White-Label

  • OAuth Redirect URL: https://oauth.n8n.cloud/oauth2/callback

  • Client ID: 694dc6e7cbb4228e2b4b5e35-mjyxod3n

  • Client Secret: (configured correctly, verified in GoHighLevel Marketplace)

  • Scope: contacts.readonly contacts.write calendars.readonly calendars.write locations.readonly

  • Allowed HTTP Request Domains: All

GoHighLevel App Configuration:

  • App Name: ProfityAI N8N Integration

  • Client ID: 694dc6e7cbb4228e2b4b5e35-mjyxod3n

  • Created: Jan 04, 2026

  • OAuth Redirect URI configured in GHL: https://oauth.n8n.cloud/oauth2/callback (matches exactly)

What I’ve Tried:

  1. Multiple attempts to connect the OAuth credential (5+ times)

  2. Verified all configuration settings match between n8n and GoHighLevel

  3. Checked that the OAuth redirect URI is identical in both systems

  4. Confirmed GoHighLevel Marketplace app is properly configured with correct scopes

  5. Waited for potential timeouts and retried

Example Failed Callback URLs:

Questions:

  1. Are there any known issues with the HighLevel OAuth2 API integration in n8n Cloud?

  2. Can you check the server-side logs for the failed token exchange attempts?

  3. Is there a specific configuration or setup step I might be missing for GoHighLevel OAuth2?

  4. Could this be related to the Authorization URL being set to “White-Label” instead of a specific endpoint?

Use Case:
I’m building a workflow to automatically book appointments in GoHighLevel CRM when triggered by a webhook. The HTTP Request node needs OAuth2 authentication to call the GoHighLevel Calendar Events API endpoint.

I’d appreciate any insights or assistance you can provide to resolve this token exchange issue.

Thank you,
Fabio

2

“Fabio_91”, I looked into the issue you’re experiencing and it seems like GoHighLevel is trying to exchange the authorization code for an access token on your n8n Cloud workflow’s oauth.n8n.cloud/oauth2/callback endpoint. One solution could be to set the timeout to 30000 (30 seconds) in your Vector Store Retriever node, which should give it enough time to complete the OAuth request. Alternatively, you can try using the `maxRedirectCount` setting on your OAuth Redirect URL to increase the number of redirects and hopefully prevent the “Something went wrong” error. Let me know if this helps!