Bug: YouTube "Set Thumbnail" Action returns 403 Insufficient Authentication Scopes (despite full permissions)

Hi Pabbly Support Team,

I am experiencing a persistent issue with the YouTube integration, specifically the "Set Thumbnail" action. Every time I run the action, it fails with a 403 error.

Error details:

• Error code: 403

• Error reason: ACCESS_TOKEN_SCOPE_INSUFFICIENT

• Error message: Request had insufficient authentication scopes.

• Error status: PERMISSION_DENIED



My Setup:

• Video ID: I am mapping the correct 11-character video ID (YouTubeResponse id, e.g., a_oEHERrehY) from a previous step where the video upload completes successfully.

• Image URL: I am providing a direct, publicly accessible URL to a valid .png file.

Troubleshooting steps I have already taken (that did not solve the issue):

1. I have completely removed the YouTube connection and created a fresh "Add New Connection".

2. During the Google OAuth popup, I made absolutely sure to check all the permission boxes to allow Pabbly to manage my YouTube account and videos.

Despite having all scopes granted in the Google popup, the 403 error persists. Could there be an issue or a missing scope request in the Pabbly YouTube app specifically for the Thumbnail endpoint?

Any help to resolve this would be greatly appreciated!

Best regards,
Thomas Bøge

Sorry my mistake...
It is not possible to upload a Thumbnail to a shorts...
Best regards,
Thomas Bøge

Hello Thomas,

Thank you for reaching out and for sharing the detailed information about the issue you faced with the YouTube integration. I truly appreciate the effort you put into explaining your setup and the troubleshooting steps you already tried.

I understand how frustrating it must have been to encounter the 403 error despite carefully reconnecting and granting all permissions. Your observation is absolutely correct—YouTube currently does not allow custom thumbnails to be uploaded for Shorts. This limitation is on YouTube’s side, and unfortunately, the “Set Thumbnail” action will not work for Shorts videos.

I’m glad you caught this detail and clarified it in your follow-up message. Please rest assured that your initial setup and approach were correct, and the issue is not due to anything you missed—it’s simply a restriction from YouTube’s API.

If you are working with standard YouTube videos (not Shorts), the thumbnail upload should work as expected. If you face any issues with regular videos, please let us know, and we’ll be happy to investigate further.

Thank you again for your patience and understanding.

Thanks & Regards,

Adeel Akhtar
🌐 Pabbly.com