Diskferry

Windows says "You need to format the disk": Mac drives

You plug in a drive from a Mac and Windows says "You need to format the disk in drive E: before you can use it. Do you want to format it?" The answer is Cancel. The drive is not broken; Windows just cannot read its format.

Why Windows asks

Windows reads FAT, exFAT and NTFS. A drive formatted on a Mac uses APFS or Mac OS Extended (HFS+), which Windows does not recognize, so it treats the drive as blank. The TransMac readme puts it plainly: "Windows does this because it does not recognize Mac format disks. Just cancel that window without formatting" (TransMac readme, checked 30 October 2026).

Disk Management may also offer to initialize the disk. Cancel that too.

What to do instead

  1. Cancel the prompt and do not open the drive in File Explorer again, so the prompt is not clicked by accident.
  2. Open the drive with an app that reads Mac formats. Diskferry finds it with Find Mac drives, opens it read only and lets you browse and preview for free.
  3. Copy what you need to the PC. Each copy is verified against the original.
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If you already clicked Format

A format writes a new, empty Windows file system over the start of the drive. Diskferry reads intact APFS and Mac OS Extended volumes; it is not a recovery tool and cannot read a drive that has been reformatted. Stop writing to the drive (do not copy anything onto it) and use data recovery software or a recovery service. The less is written to it, the better the chances.

If you want the drive to work on both Mac and PC

Copy the files off first, then erase the drive as exFAT on the Mac. Format a drive for Mac and Windows

Questions

Will cancelling the format prompt hurt the drive?

No. Cancelling changes nothing. Only choosing Format erases the drive.

Why does the drive get a letter but no files?

Windows sometimes assigns a letter to a partition it cannot read. Opening that letter leads to the format prompt. Ignore the letter and read the drive with a Mac drive app.

Last updated 30 October 2026. Still stuck? Support replies in person.

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