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Disc Utility fails to erase and reformat flash drives- both new ones and ones with content on them.

Disc Utility fails to erase and reformat flash drives- both new ones and ones with content on them.

I attempted both Fat Dos & Mac Journaled formatting and operation failed/ invalid argument. Flash drives unmounted from computer. [screen] When I reinsert the drives they will not mount. 2 brand new $20 each PNY flash memories & a used Kingston. Running High Sierra OSX software 10.13.6 Disc Utility always worked perfectly in past. Russ [needed photos for real estate and insurance companies].

MacBook, macOS 10.13

Posted on Jan 25, 2020 8:39 AM

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Posted on Jan 25, 2020 10:44 AM

Do other things work in the same USB ports?


Safe Boot from the HD, (holding Shift key down at startup), does the problem occur in Safe Mode?


Safe mode attempts to repair Disks & clears lots of caches, so if Safe Mode works try again in regular boot.

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7 replies

Jan 25, 2020 1:22 PM in response to BDAqua

I was able to erase and format unmounted flash drives on second attempt. They appeared in disc utility grayed out but not on desktop. I was able to click onto the drives and they lit up and first aid/erase lit up. so I tried reformatting in Mac journaled and Windows. It worked! I'm suspecting glitches in flash memory drives or possible dirty USB ports- but I blew them with compressed air last month and laptop lives in a very clean environment; but it's 10 years old now And I have noticed occasional issues when plugging into my printer also. So maybe it's the USB ports [2]. A Apple refurbished 1 year old MacBook Pro is on my wish list. Thanks for your help. Russ.

Jan 25, 2020 2:35 PM in response to russtodd

I'm going to buy some Sandisk thumb drives and play around some more since I have quite a bit of work to do in Photos and I am curious about questionable USB ports. I did put a new battery and SSD hard rive into this old MacBook about 5 years ago. It's 10.3 years old now. Amazing. Used only part time might explain it's long life. I will miss the long key stroke key pad and build in DVD drive.... oh and the magnetic charger- they should still have that on the new MB Pros. They skimped. Russ

Disc Utility fails to erase and reformat flash drives- both new ones and ones with content on them.

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