Reporting bugs to the Chromium dev team

I was trying out the new experimental Native File System API in Chromium, that's still hidden behind a feature flag and in an origin trial. Since it's still being worked out, there are sure to be bugs and I've discovered one on my first try of using it.

When you connect an Android device on a Windows machine, if you just try to select a file using window.chooseFileSystemEntries(), it results in a “can't open files in this folder because it contains system files” error.

My guess is that the problem is that the Native File System API does not have proper support for the MTP protocol used by Android, even though that is one of the design goals of the API:

Apps that want to work with “libraries” of certain types of files. I.e. photo managers, music managers/media players, or even drawing/publishing apps that want access to the raw font files for all fonts on the system.

I reported the bug, and quickly realised I need to provide properly detailed steps to enable them to reproduce the issue before a Chromium developer will look into it. For now, this is the best that I got:

  1. Check that the #native-file-system-api flag is enabled in chrome://flags
  2. Connect Android device to Windows laptop
  3. Go to
  4. Click on File->Open, navigate to the connected Android device and attempt to open a text file
  5. Chrome responds with a “Can't open this file” error message.

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