Get 500 Internal server error when trying add new track to playlist

[Peter1205]

I'm using this api to add new track to playlist.

https://api.spotify.com/v1/playlists/{playlist_id}/tracks

 But when I added 11,000 track successfully, there no way to add more. Is it limit track number per playlist?

Why I get status code 500 but not 403? From document of spotify for developers:

"Trying to add an item when you do not have the user’s authorization, or when there are more than 10.000 items in the playlist, returns error 403 Forbidden."

Is there anyway to add more than 10,000 track per playlist? Do I have upgrade my account to premium?