SanDisk® Global Customer Support (US)
Converting external drive to Apple File System (APFS) format
If you receive an error while converting your external drive to APFS please read the following:
1. Open disk utility on your Mac OS 10.13 High Sierra
2. Connect your external drive into your USB port
3. Click on "Show all devices"
4. Highlight the main drive (left side window pane) and then click on the Erase tab.
5. Make sure format is "Mac OS Extended Journaled" and ensure that the scheme is set to "GUID Partition Map"
6. Click on erase button
7. Right click on that partition of the drive "untitled" or "No Name"
8. Select "convert to APFS"
9. Please wait during conversion process. Once done click "done"
10. Right click on drive "untitled" from desktop
11.Select "get info"
12.Under general you will see APFS under the "Format"
Details 
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