mountvol Y:/s <Enter> returns: The directory is not empty. I'm trying to increase partition space to install MS 25H2 update

The error message "The directory is not empty" when using the mountvol Y:/s command indicates that the target directory (Y:) is not empty, which prevents the operation from succeeding. To resolve this issue, you need to ensure that the target directory is empty before attempting to mount the volume again.

If you are trying to increase partition space to install the MS 25H2 update, you may want to consider freeing up space on your operating system disk. Here are some steps you can take:

1. Check Disk Space: Ensure that your operating system disk has at least 20 GB of available space for updates.
2. Free Up Space: Uninstall unused applications, delete unnecessary files, or move files to another disk to create more space.
3. Use External Storage: If you cannot free up enough space, consider using an external drive during the update process.
4. Disk Management: You can also use Disk Management to resize partitions if necessary, but be cautious and back up your data before making changes.

If the issue persists, you may need to investigate further or contact Microsoft Support for assistance with the update process.