How to do if external hard drive can't be recognized on Windows computer after using it on Mac.

This is common question, especially, when connecting external hard drive between Mac and Windows. Due to the different file system format, the drive might not be recognized on Windows computer after using it on Mac, mostly, you will see a 200MB EFI partition and the other unallocated partition in Disk Management, here is how you can fix the problem by using diskpart command.

Here are steps about how to delete EFI partition:

1.Hit "Windows Key + R" to open the run dialogue box.  Enter diskpart and click  "OK" to open a black command prompt window.

2. Then, enter "list partition", it displays all the volumes on the hard drive.

3. Please enter "select disk(number) ", it identifies which disk volume letter you want to remove. (For example, here 3 stands for volume letter)

4. Please enter "list partition" again, it will list out the partitions on the disk, then enter "select partition (number)", It identifies which partition you want to remove. (For example, here 1 stands for the volume letter.

5. Then, enter "delete partition override", it removes the EFI partition from Windows disk. Finally, type "exit" to close the windows when you receive the message that says, "DiskPart successfully deleted the selected partition".  After that, you could go back to Disk Management and repartition the drive.