[Bug]: I/O errors on host when using mapped folders

[jeremy-visionaid]

Windows Sandbox version

0.5.1.0

Windows build number

10.0.26100.0

Other software

Error seems to be reproducible with any host app writing to the mapped folder, but it's easy to reproduce with either Chrome or Edge.

Steps to reproduce the bug

1. Share the host Downloads folder. e.g.

<Configuration>
  <MappedFolders>
    <MappedFolder>
      <HostFolder>C:\Users\user\Downloads</HostFolder>
      <SandboxFolder>C:\Users\WDAGUtilityAccount\Desktop\Downloads</SandboxFolder>
      <ReadOnly>true</ReadOnly>
    </MappedFolder>
  </MappedFolders>
</Configuration>

2. Open the Sandbox
3. Download a large file

Expected result

Download should succeed

Actual result

Chrome or Edge reports "Couldn't finish download"

Included System Information

No response

[Colonel-Badger]

This has been present for ages. Anything over 100 MB fails.

[kvega005]

Could you please file feedback via Feedback hub? This will help us collect the necessary logs.

1. Open Feedback Hub app
2. Click "Report a problem"
3. Fill in the relevant information.
4. Under "Choose a category", select from the dropdowns: Security and Privacy and Windows Sandbox.
5. Go to the "Add more details" section and click "Recreate my problem".

[jeremy-visionaid]

Done: https://aka.ms/AAwuvzr

[jeremy-visionaid]

Seems like it's got worse... I don't think it even managed 1 Mb without encountering a problem.