Media Player called in state 0, error (-38,0)

Solution 1:

You need to call mediaPlayer.start() in the onPrepared method by using a listener. You are getting this error because you are calling mediaPlayer.start() before it has reached the prepared state.

Here is how you can do it :

mp.setDataSource(url); 
mp.setOnPreparedListener(this);
mp.prepareAsync();

public void onPrepared(MediaPlayer player) {
    player.start();
}

Solution 2:

It seems like Error -38 means a state-exception (as the error-message indicates). For example if you call start(), before the song was ready, or when you call pause(), even if the song isn't playing at all.

To fix this issue check the state of the mediaPlayer before calling the methods. For example:

if(mediaPlayer.isPlaying()) {
    mediaPlayer.pause();
}

Additionally, the MediaPlayer is sending event-messages. Even if you do not need the prepared-event (although it would be a good idea to not start the playback before this event was fired) you must set a callback-listener. This also holds true for the OnErrorListener, OnCompletionListener, OnPreparedListener and OnSeekCompletedListener (if you call the seek method).

Listeners can be attached simply by

mediaPlayer.setOnPreparedListener(new OnPreparedListener() {
    @Override
    public void onPrepared(MediaPlayer mp) {
        // Do something. For example: playButton.setEnabled(true);
    }
});