iMac 27 suddenly will not allow writing to, or deleting files on flash drives

[Sandy Scott]

This problem started today. When I plug in a flash drive (I have tried two that worked yesterday) into either a USB port on a hub that I have or directly into the back of the iMAC, the drive is immediately recognized on the desktop. I can read files on the flash drive, but suddenly, I cannot drag a file on to it to copy it and I am not allowed to delete a file on the two flash drives that previously worked. When I attempt to drag a file to the flash drive, I get a circle with a diagonal line through it. I am running Yosemite. Again, as recently as yesterday, I was able to write to the two flash drives I tried. Interestingly I can write to a Seagate drive hooked up to a USB port - just not the flash drives.

 

[Spawn_Dooley]

have you tried Get Info ~> Sharing & Permissions~> Ignore Ownership On This Volume?

 

[Sandy Scott]

have you tried Get Info ~> Sharing & Permissions~> Ignore Ownership On This Volume?

Under sharing & permissions it does say, "You can only read" which explains the issue, but I don't see where you can opt for the ignore ownership on this volume. Where can I find that?

 

[Spawn_Dooley]

Should be at the very bottom

You should be able to unlock the padlock & change the permissions back to read/write

 

[Sandy Scott]

Should be at the very bottom

You should be able to unlock the padlock & change the permissions back to read/write

It is at the bottom, but it shows no ability to change anything:

 

[Spawn_Dooley]

Have you tried rebooting your Mac?

How large is the file you are trying to drag onto the drive?

You could try Disc Utility & "Verify Disk" but I think there might be a corruption I can't say 100% for sure but you might have to back up the drives contents if possible then reformat