403 Forbidden on Add Tracks to Playlist API despite valid scopes

[soundsdj]

I have a Next.js app hosted on Vercel.

The app successfully:
- Authenticates user
- Returns playlist-modify-private
- Returns playlist-modify-public
- Returns user-read-private
- Creates playlists successfully
- Searches tracks successfully

However:

POST /v1/playlists/{playlist_id}/tracks

always returns:

403 Forbidden

The playlist is owned by the authenticated user.
The same token successfully creates the playlist.

Track URIs are valid Spotify track URIs.

Example failing endpoint:
POST https://api.spotify.com/v1/playlists/{playlist_id}/tracks

Request body:
{
"uris": [
"spotify:track:320lwWuMpZ6b0aN2RZ0eMS"
]
}

Any ideas why Spotify allows playlist creation but blocks adding tracks?

[Ximzend · Accepted solution]

Hi @soundsdj 

You should use items instead of tracks. This also applies to episodes, shows, albums, and audiobooks.

Look for all the changes to the API in this page.

Cheers!