VideoPlayer error on seek

I have a problem using the video player - I can load a video and seek anywhere in the video, but sometimes (not predictable when) on seek Unity throws an error and I can’t figure out why and how to work around it. Here’s my code:

[SerializeField] private RawImage rawImage;
[SerializeField] private Slider seekSlider;

VideoPlayer videoPlayer;

    void Start() {
        videoPlayer = gameObject.AddComponent<VideoPlayer>();
        videoPlayer.renderMode = VideoRenderMode.APIOnly;
        videoPlayer.playOnAwake = false;
        videoPlayer.source = VideoSource.Url;
        videoPlayer.prepareCompleted += player => rawImage.texture = player.texture;
        seekSlider.onValueChanged.AddListener(v =>  videoPlayer.time = v);

        videoPlayer.url = *path to local .mp4 file*;

The video plays nicely. Seeking works anywhere in the video. Except sometimes (about 1 in 10) when it gives me the following error:

WindowsVideoMedia error 0xc00d6d60
while reading
(path to my mp4 file)

IMFSourceReader::WaitForSample in
ReadSample Error details: A valid type
has not been set for this stream or a
stream that it depends on. Track
types: Unreadable Track

I am on Windows 10, using Unity 2019.3.2f1

Any ideas?

I also tried making sure to not seek until the current seek has finished, using a seekable flag, adding this to Start()

        seekSlider.onValueChanged.AddListener( v => {
            if(seekable && videoPlayer.canSetTime && videoPlayer.isPrepared) {
                videoPlayer.time = v;
                seekable = false;

     videoPlayer.seekCompleted += player => seekable = true;
     seekable = true;

But that did not change any of the described behaviour (while it does make seeking with the slider more enjoyable).