VideoPlayer cannot play url for local file on Android 10 devices,

VideoPlayer doesn’t play a movie read from a local file on Android 10 devices.

I made a class that downloads a movie file from a specified url and save it at local storage (Application.temporaryCachePath) and play it using VideoPlayer (.url = file://[file path]).

This program works well on iOS devices and Android devices except Android 10.
It also works well when I play the movie by passing the remote url to VideoPlayer directly. (in other word, Streaming.)
Handheld.PlayFullScreenMovie work well too.
So I think the devices have a capability to play the movie file.

Url without [file://](.url = [file path]) doesn’t work.

videoPlayer.errorReceived += (vp, message) => {
    Debug.LogError(message);
};

says

VideoPlayer cannot play url : file:///....
Cannot read file.

Is this a unity bug?
Unity version is 2018.3.12f1

Thank you.,

https://forum.unity.com/threads/error-videoplayer-on-android.742451/#post-5028434