I have had an Iomega 1T backup disc for my iMac Pro for 4 years (LPHD-UPC) which has performed perfectly. However since the last update (to Monterey 12.2) I get the message:
"Files can't be copied onto the back-up disk because it is read-only"
What has happened? What can I do about it?
iMac Pro
Hi Lottie51
Before erasing the external drive there is one extra check you can do that might resolve the problem.
Open Finder, locate the external disk in the list of drives, mouse-right-click on the disk and from the pop-up context menu click "Get Info"
An Info pane will open, at the bottom of the info pane look under Sharing and Permissions.
To be able to write and read to the disk you should see (normally) three or more users, "your own name", "staff" and "everyone"
Occasionally, when upgrading a macOS the users and permissions may become scrambled.
Against "your own name" you should have Read & Write Privilege, "staff", if present, should also be Read & Write, finally, "everyone" is normally "Read only".
To be able to use the disk for a Time Machine backup you must have Read & Write privilege.
If your name is missing from the list of users, or you only have "Read only" privilege, click the lock symbol at the lower right of the info pane and enter your user password, then, if your name is already in the list click the privilege box next to your name and change the Privilege setting to Read & Write.
If your name is missing from the list of users click the "+" symbol at the bottom of the info pane and a pop-up window will open, look for your name in the list , click it to choose and then click the "Select" button.
The final step is to apply any changes you make to users or privilege settings.
To the right of the "+ -" boxes is a circle with three dots, click that circle and a pop-up menu appears, click "Apply to enclosed items"
The revised permissions and ownership will now be written to the disk itself, and all the contents.
This will take a long time, several hours if the disk has a lot of small files and folders stored.
After making any changes it is best to leave the Mac alone while this change propagates across the disk, for a 1TB drive it might take four hours to complete.
When the permissions have been updated, reboot the Mac and then try Time Machine again to see if it can now write to disk.
An extra tip, when looking at the list of users and permissions if you see under users, "unknown" or "searching" this is an indication that permissions have been set for a user that can not be identified. If this is the case, reboot the Mac into Recovery-Mode, open Disk Utilities and use First Aid on all your Mac internal and external disks so that the correct user can be identified and this error repaired.
Extra tip2, when applying First Aid from Disk Utilities it must be applied in the correct sequence, otherwise it will fail to repair permission and missing user problems.
Expand the "tree" view for each individual disk to view the nodes and always apply First Aid from the bottom up, Volumes first, at the bottom of the tree, then Containers, in the middle, and finally Disks, at the top.
If you start with Disks, for those disks that do have Volumes, Containers and Disks, user permissions are not repaired for any of the nodes below "Disks".
https://support.apple.com/en-us/HT210898
HTH
Will.
Hi Lottie51
Before erasing the external drive there is one extra check you can do that might resolve the problem.
Open Finder, locate the external disk in the list of drives, mouse-right-click on the disk and from the pop-up context menu click "Get Info"
An Info pane will open, at the bottom of the info pane look under Sharing and Permissions.
To be able to write and read to the disk you should see (normally) three or more users, "your own name", "staff" and "everyone"
Occasionally, when upgrading a macOS the users and permissions may become scrambled.
Against "your own name" you should have Read & Write Privilege, "staff", if present, should also be Read & Write, finally, "everyone" is normally "Read only".
To be able to use the disk for a Time Machine backup you must have Read & Write privilege.
If your name is missing from the list of users, or you only have "Read only" privilege, click the lock symbol at the lower right of the info pane and enter your user password, then, if your name is already in the list click the privilege box next to your name and change the Privilege setting to Read & Write.
If your name is missing from the list of users click the "+" symbol at the bottom of the info pane and a pop-up window will open, look for your name in the list , click it to choose and then click the "Select" button.
The final step is to apply any changes you make to users or privilege settings.
To the right of the "+ -" boxes is a circle with three dots, click that circle and a pop-up menu appears, click "Apply to enclosed items"
The revised permissions and ownership will now be written to the disk itself, and all the contents.
This will take a long time, several hours if the disk has a lot of small files and folders stored.
After making any changes it is best to leave the Mac alone while this change propagates across the disk, for a 1TB drive it might take four hours to complete.
When the permissions have been updated, reboot the Mac and then try Time Machine again to see if it can now write to disk.
An extra tip, when looking at the list of users and permissions if you see under users, "unknown" or "searching" this is an indication that permissions have been set for a user that can not be identified. If this is the case, reboot the Mac into Recovery-Mode, open Disk Utilities and use First Aid on all your Mac internal and external disks so that the correct user can be identified and this error repaired.
Extra tip2, when applying First Aid from Disk Utilities it must be applied in the correct sequence, otherwise it will fail to repair permission and missing user problems.
Expand the "tree" view for each individual disk to view the nodes and always apply First Aid from the bottom up, Volumes first, at the bottom of the tree, then Containers, in the middle, and finally Disks, at the top.
If you start with Disks, for those disks that do have Volumes, Containers and Disks, user permissions are not repaired for any of the nodes below "Disks".
https://support.apple.com/en-us/HT210898
HTH
Will.
Hi Lottie.
Did you try to click the “Lock” symbol first, the “+-“ keys are “greyed” out until you unlock the settings?
Normally, as the principle user-administrator, you can alter sharing and permissions for any disk, folder or file on the Mac but external disks are a little different, if that disk is no longer recognised as “belonging” to you and has become locked to another user then you have no rights over it, and cannot change its attributes. This is especially the case if the disk was originally formatted as NTFS, which macOS used to accept as a valid format to write to but now only accepts the HFS+ format for Time Machine.
Out of curiosity, were you just updating Monterey from one build to a later build or were you upgrading from a much older macOS such as e,g. High-Sierra?
If the disk is showing as “Read-Only” under “Sharing & Permissions”, cannot be “Unlocked” to allow modification, is showing in the info-pane as formatted in NTFS and cannot be repaired under First Aid using Disk Utilities, then the only possible steps are to format a new disk in HFS+ format and copy over the entire read-only contents of the old disk to it, the new disk will belong to you and being in HFS+ format you can then attempt to apply Read&Write permission to the contents, or, reformat the old disk HFS+ and start a new Time Machine backup.
Personally, I would recommend using a brand new disk and just archive the old one.
With Time Machine usage the life of a typical spinning-platter disk is around five to seven years before they become worn out and require replacement, and, as of today, expensive SSD’s are still not suitable for long-term storage since each data cell in the SSD gradually loses it’s charge if not regularly over-written, this makes them unreliable for Time Machine, or any other long-term archival purposes.
Large capacity conventional spinning-platter disks are really inexpensive right now so that would be my recommendation, to replace it.
If you do want to try and reformat the old external drive you may find that Disk Utilities when the Mac is in normal mode will not allow you to do this, since you do not “own” the disk, if this is the case try booting into Recovery-Mode and use Disk Utilities from there.
If you are still prevented from formatting the drive in Disk Utilities, even in Recovery-Mode, then connect the disk to a Windows Machine and reformat the drive exFAT on that platform, Windows will not care who owns the disk.
After you move the disk back to your Mac reformat the disk as HFS+ using Disk Utilities and then connect to the disk in Time Machine and all should be ok.
Whenever a macOS upgrade is due, trigger a Time Machine immediate backup and when complete power down the Mac, disconnect the external disk, start the Mac and carry out the upgrade then, after the update is complete reverse the process.
That should minimise the chances of the same thing happening again, that is if this was a permissions issue and not because the disk was formatted NTFS.
Sorry I could not think of anything else to suggest as a way out of this impasse on this occasion.
Will.
Lottie51,
Yes, it does sound like the issue could possibly be your external hard drive. One option you could consider is erasing the external hard drive and then trying to set it up again to work with Time Machine. You could also try testing Time Machine with another external drive (if available).
If you have any further concerns or questions about this issue, you can contact Apple Support for further assistance here: Contact Apple Support
Best regards.
Hi Lottie51,
We understand that you are now seeing a message that files cannot be copied to your external hard drive because it's read-only. Does this issue continue if you restart your iMac Pro? Log out, sleep, wake, restart, or shut down your Mac It can seem like a simple step, but it can sometimes help.
Also, does this happen in a temporary new user? Set up users, guests, and groups on Mac A new user has no custom or changed settings and can help determine if this issue is happening with any user or specifically your user.
Take care.
Lottie51,
If there is something going on with the external hard drive, you might not be able to restore it when downgrading macOS. What happens when you view your external hard drive in Disk Utility or does it not appear in Disk Utility at all? You should still be able to run First Aid on the external hard drive.
If you prefer to try to downgrade, you could backup your data an additional way then try. The articles below could help with that:
Cheers.
Lottie51,
Thanks for trying those steps for us and letting us know the results. Please check out the following article to see if it might help: If you can't back up or restore your Mac using Time Machine - Apple Support
Best wishes.
No, it is still there despite restarting the iMac. And becoming a Guest User has still produced the same “Time Machine couldn’t complete the backup to Iomega_HDD. Files can’t be copied onto the backup disk because it is read-only”.
No. Back to the same problem. The back-up disk is reported on as read-only. And because it is external (via a USB) then Disk Utilities doesn't do First Aid. Do I need to downgrade from Monterey 12.2?
Thank you. I did manage to run First Aid after all, but ultimately "The Operation Failed" Something about unable to check the volume completely (though it took 20 minutes to get that far).
So do I consider the external hard drive to be at fault?
Thanks Will,
Alas, when trying to change Sharing & Permissions for the Iomega_HDD the + and - remain obstinately greyed out, presumably because above the table of users is the statement “You can only read”. Does that sound like a Monterey issue rather than the ext drive?
Mac upgrade affecting my Iomega external HDD?
