External Hard Drive became Read Only All of a Sudden

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radar1989 Author

Level 1

13 points

External Hard Drive became Read Only All of a Sudden

My external hard drive (Mac OS Extended) became read-only all of a sudden. This happened after an unsuccessful Time Machine backup from yesterday due to inadequate disk space. After I cleaned up some space and initiated a Time Machine backup manually, the drive became read-only. "Get info" shows the following. As you can see, under sharing & permissions, it says "You can only read", and there is no way for me to modify the permissions even if I click the lock on the lower right.

I also ran first aid in disk utility and it failed with the following error code:

My 1TB drive is almost full and the last thing I would want to do is erase and reformat, which would require me to buy a new external hard drive just to transfer the data. I looked everywhere online and most are solutions to drives formatted as NTFS, but mine is mac OS extended. And I'm running OS High Sierra. Please help me! Thanks!

MacBook Pro TouchBar and Touch ID, macOS High Sierra (10.13.2)

Posted on Dec 26, 2017 10:45 AM

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Answer 1

Niel

Community+ 2025

Level 10

741,473 points

Dec 26, 2017 10:52 AM in response to radar1989

You may be able to repair the issue with a product such as DiskWarrior, but you should put the data onto another drive; regardless of anything else, the one you have will eventually fail.

(156236)

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Answer 2

Kappy

Level 10

362,007 points

Dec 26, 2017 10:54 AM in response to radar1989

You have a pretty serious problem in that the drive may have failed and is certainly corrupted and not usable. Are you able to boot the machine or does that now fail? If the drive mechanism and firmware are actually OK, then you would need to reformat the drive and lose your data. I assume your concern is because you don't have a backup you could restore?

Do you have access to an external drive with a bootable system on it? Or access to another Mac with FW800 or Thunderbolt ports. You would need adapters for each unless you have another 2017 Mac you could use.

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Answer 3

Dec 30, 2017 2:00 PM in response to radscoot

I had the same problem. I use the external drive for Time Machine and when I upgraded to High Sierra it changed the permissions to read only for everyone except System and Wheel. It happened first on my iMac. After I'd discovered what was happening I tested it by upgrading to High Sierra on my MacBook. Same result.

John Galt helped me understand what was happening and why. You can read that discussion here. Re: Can't change permissions on external drive

Hard drives are not expensive so I've decided to go with the flow and dedicate one hard drive to Time Machine on the iMac and one to TM on the MacBook. I'm using another external drive for other storage needs, e.g. large video files.

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Answer 4

radscoot

Level 1

9 points

Dec 30, 2017 6:27 AM in response to radar1989

I have the exact same problem. Showed up right after I upgraded to High Sierra.

External drive that contains my IPhoto and IMovie library is now read only.

I have not fixed it yet but what I did do to confirm it’s not an issue with the drive is,

I have Windows 7 running in Bootcamp on same MBP. The same external drive is read and write no problem from there.

This is some kind of glitch with High Sierra. I have my time Machine on another external drive and at this point I will not plug it into the MAC until I find a fix for this issue.

Hopefully a simple fix for this issue will be found.

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Answer 5

Dec 30, 2017 8:33 AM in response to radscoot

radscoot wrote:

I have the exact same problem. Showed up right after I upgraded to High Sierra.

External drive that contains my IPhoto and IMovie library is now read only.

I have not fixed it yet but what I did do to confirm it’s not an issue with the drive is,

I have Windows 7 running in Bootcamp on same MBP. The same external drive is read and write no problem from there.

This is some kind of glitch with High Sierra. I have my time Machine on another external drive and at this point I will not plug it into the MAC until I find a fix for this issue.

Hopefully a simple fix for this issue will be found.

Your problem is different than that being discussed in this thread. Your external drive is likely formatted NTFS for Windows. You likely have a third party app installed that allowed you to use the NTFS drive when booted into your Mac side. When you updated your Mac operating system it likely made the third party app no longer compatible. See if the third party app developer has an updated app that works with your updated operating system.

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Answer 6

radscoot

Level 1

9 points

Dec 30, 2017 1:22 PM in response to BobTheFisherman

I don’t understand why it works in Window's and not on my Mac anymore either. I just tried it as I had nothing to lose. All I know is I have been using this Mac formatted drive for my iphoto library and videos for a number of years and right after I installed High Sierra the drive is read only and I get the same errors as the Original poster.

Based on what I have seen in my research there is lots of other people having the same issues and I was hoping to find a solution here.

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Answer 7

radar1989 Author

Level 1

13 points

Dec 26, 2017 11:06 AM in response to Niel

what do you mean by "the one you have will eventually fail"? Is this hard drive gonna cause me more problems in the future even if I'm able to fix it this time?

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Answer 8

radar1989 Author

Level 1

13 points

Dec 26, 2017 11:08 AM in response to Kappy

Right. I don't have enough space to back up my data in the external hard drive. I might just go and get a new one and copy everything over.

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Answer 9

Kappy

Level 10

362,007 points

Dec 26, 2017 11:27 AM in response to radar1989

Good idea. Don't leave the computer running until you are ready to format and partition the new drive and copy your files.

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Answer 10

Niel

Community+ 2025

Level 10

741,473 points

Dec 26, 2017 11:31 AM in response to radar1989

Yes. All drives will eventually wear out; your files should be on at least two.

(156238)

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Answer 11

radscoot

Level 1

9 points

Dec 30, 2017 12:18 PM in response to BobTheFisherman

Same Problem as OP.

Drive is MAC OS Extended and is now Read only after Install of High Sierra.

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Answer 12

Dec 30, 2017 12:28 PM in response to radscoot

If the drive is formatted Mac then it can not be read/write from Windows 7 as you stated in your post.

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Answer 13

Dec 30, 2017 1:26 PM in response to radscoot

So when you are in Windows what format does Windows say the drive is? Post the screen shot as you did from the Mac side but from within Windows using the Windows format utility.

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