How to copy Asset folder content into internal storage in Xamarin.Android?

I need to copy the content in a folder located in Assets in my Xamarin.Android project. There are more than 10 files in my Content folder and I need to create a folder called Models in my application's data folder and copy the content into it. So I have done following steps.

 private async Task copyFileAsync()
    {
      
        var outputName = Application.Context.GetExternalFilesDir("").AbsolutePath + "/Models";
        if (!System.IO.File.Exists (outputName))
        {
            Directory.CreateDirectory(outputName);
        }
        AssetManager assetManager = this.Assets;
        String[] files = null;
        try
        {
            files = assetManager.List("html/Model1/Content");
        }
        catch (System.IO.IOException e)
        {
            System.Console.WriteLine("tag", "Failed to get asset file list.", e);
        }
        foreach (String filename in files)
        {
           
            string filePath = System.IO.Path.Combine(outputName, filename);
            using (var fileAssetStream = assetManager.Open(filename))
            using (var fileStream = new FileStream (filePath, FileMode.OpenOrCreate))
            {
                await copyInToLocationAsync(fileAssetStream, fileStream, filePath);
            }
            
           System.Console.WriteLine("------COPIED------------------------");
            
        }

       
    }

private async Task copyInToLocationAsync(Stream fileAssetStream, Stream fileStream, string path)
    {
        byte[] buffer = new byte[1024];
        int b = buffer.Length;
        int length;
            while ((length = await fileAssetStream.ReadAsync(buffer, 0, b)) > 0)
            {
                await fileStream.WriteAsync(buffer, 0, length);
            }

            fileStream.Flush();
            fileStream.Close();
            fileAssetStream.Close();



        }

then in my OnCreate() method I am calling await copyFileAsync();. But my problem is I am getting a run time exception at using (var fileAssetStream = assetManager.Open(filename)) in CopyFileAsync().

This is the exception I get and 0.pf is the 1st file in my Content folder. What is the reason for this and how can I overcome this?

You lost the file's path. According to your code, the file 0.pf is in the path /Assets/html/Model1/Content. So you should pass the full path when you use the assetManager.Open. Such as:

using (var fileAssetStream = assetManager.Open("html/Model1/Content/"+filename))