Google transcoder HLS: Internal server error

Question

I'm trying to transcode a simple .mp4 file to HLS format and keep getting an error code 13 'Internal server error' from Google after a few minutes. I'm using the Java SDK. Who can help me find out what I'm doing wrong?

        VideoStream videoStream = VideoStream
            .newBuilder()
            .setH264(
                VideoStream
                    .H264CodecSettings.newBuilder()
                    .setBitrateBps(6000000)
                    .setFrameRate(120) //Output framerate will always match the input framerate
                    .setWidthPixels(width)
                    .setHeightPixels(height)
            )
            .build();

        JobConfig config = JobConfig
            .newBuilder()
            .addInputs(Input.newBuilder().setKey("input0").setUri("gs://putyoururlhere"))
            .setOutput(Output.newBuilder().setUri(output))
            .addElementaryStreams(ElementaryStream.newBuilder().setKey("video_stream0").setVideoStream(videoStream))
            .addMuxStreams(
                MuxStream
                    .newBuilder()
                    .setKey("stream")
                    .setContainer("ts")
                    .setFileName("stream")
                    .addElementaryStreams("video_stream0")
                    .build()
            )
            .addManifests(Manifest.newBuilder().addMuxStreams("stream").setFileName("stream").setType(Manifest.ManifestType.HLS).build())
            .build();