Getting JSON Format Error with Spotify Web API

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1

I’m having trouble with the Spotify Web API when trying to start playback. The API endpoint for playing music returns a 400 error saying the JSON is malformed.

Here’s the error I keep getting:

Bad Request: { "error" : { "status" : 400, "message" : "Malformed json" } }

My PHP code looks like this:

$httpClient = new GuzzleHttp\Client();
$response = $httpClient->request('PUT', 'https://api.spotify.com/v1/me/player/play?device_id='.$deviceId, [
    "headers" => [
        "Authorization" => ["Bearer " . $userToken->access_token],
        "Content-Type" => "application/x-www-form-urlencoded",
    ],
    "form_params" => [
        "track_uris" => ["spotify:track:" . $songId]
    ]
]);

When I remove the track_uris parameter, the API works fine and starts playing the last song. But with the parameter included, I get this JSON error. The data being sent looks correct to me.

Anyone know what might be causing this issue?

2

spotted the issue - you’re using form_params but spotify expects raw json data. try switching to json body instead of form encoding, that should fix the malformed error you’re getting

3

Your content type header is wrong. You’re sending application/x-www-form-urlencoded but Spotify’s API wants application/json. Switch to the json parameter instead of form_params and fix the header. I hit this exact same issue last year with playlist controls - Spotify’s really picky about getting proper JSON instead of form data, even though it’s basically the same info.

4

You’re mixing content types - you declared form-encoded data but Spotify wants JSON. Switch to the json parameter instead of form_params and change your Content-Type header to application/json. Make sure your track_uris array is properly formatted as JSON too. I ran into the same issue building a playlist manager. Spotify’s endpoints are picky about getting actual JSON objects, not form-encoded arrays, even when they look the same.