User profile for user: David Bywater
David Bywater Author
User level: Level 1
60 points

Problem backing up Photos - read write errors

Hi.

I'm trying to make a backup of my Photos file. It's about 512gb and so stored on an external 4gb drive from WB. That drive is formatted as APFS.

I'm trying to make a copy to another external drive (2gb) that is formatted Mac OS extended (Journaled). That drive has 602gb free, so there's space for it to fit.

I'm not aware of any general issues with either the hard drive or the file - the file opens fine in Photos and I can use it normally.

However when I try to click and drag the file from one window to another in Finder, it gets to about 84gb after a couple of hours then says it has a read/write error and it stops. It then undoes the whole thing and I'm stuck.

I've also tried copying to a different 2GB external drive and get the same issue.

I have the 4gb drive partitioned with 1.5GB dedicated to a Time Machine backup on part of that 4gb drive and 2.5GB for files generally.

When I try First Aid on the drive it says it can't unmount the drive to check for errors. I'm assuming that's because of the TM partition perhaps?

I have been able to 'Show Package Contents' for the Photos file and individually copy all the folders with the photos in, but that's not really a proper backup of the whole Photos file and I foresee problems should I ever need to rely on restoring things that way.

That process did also throw up some read/write errors, but it had stopped the transfers and when I resumed them, they carried on and completed. All files look fine.

I have seen some other posts with people having problems after the Sequoia release, so perhaps it's related in some way.

Any tips on how to get one whole file from the external to another would be appreciated.

Perhaps I best start by trying first aid on the drive, if I can work out how to unmount it, though I suspect I will still have the same problem and I wonder whether it's anything to do with memory issues in moving such a large file in one go. I'm running Sequoia 15.5 on a 2019 2.3ghz 8 core Intel Macbook Pro with 16gb 2400 Mhz DDR4 ram.

Thanks in advance to the amazing community here who always seem to pull through for me.



MacBook Pro 15″, macOS 15.5

Posted on Jun 3, 2025 10:49 AM

Reply

Similar questions

9 replies
User profile for user: léonie
léonie
User level: Level 10
203,145 points

Jun 4, 2025 6:08 AM in response to David Bywater

You mention that the two external drives are formatted APFS and MacOS Extended (Journaled). These formats are supported by Photos, but you do not mention if the format of one of the drives is case-sensitive. If one is case-sensitive, the other should be it as well. Better would be, if neither of them is case-sensitive.

In addition to the problem with Time Machine volumes - sometimes you may be seeing the file copy errors, if one of the files is damaged or the file name contains special characters. In tap case it will help to use cloning software to copy the Photos Library, or to open the package of the Photos Library and to copy the internal folders separately. For more details see this user tip: How to avoid the Error -36 when copying a Photos Library - Apple Community


Reply
User profile for user: Richard.Taylor
Richard.Taylor
User level: Level 7
22,560 points

Jun 4, 2025 8:19 AM in response to David Bywater

You didn't say how much free storage you have on your Mac-- less than 10% free could be an issue.


Time Machine needs to be on its own volume with nothing else in that volume. You can have several volumes on a single disk drive. In APFS the volumes can dynamically vary in size depending on the need. Apple recommends that the drive be twice the size of the Mac's storage, but I think that's more about how much you actually use rather than the full size of your internal drive. I have a 4TB drive with 3 volumes, and TM is using 1.6 TB on one of the volumes.


I periodically copy my Photos Library packages to a separate drive. I don't want every backup on the same drive! A single drive failure would kill everything at once!


I also keep

Reply
User profile for user: David Bywater
David Bywater Author
User level: Level 1
60 points

Jun 9, 2025 9:55 AM in response to Richard.Taylor

I don't think I have actually lost any files. I wonder if it's a hard drive issue rather than an issue with the actual data.

By copying the folders individually from the 4TB drive I had random stops for each of the folders in the 'originals' folder, but there was an option next to the folders to 'resume' the transfer and when I did, those files copied along with the rest of the other files.


To create the new backup, rather than do that again I copied the folders from the 2nd drive (a 2TB drive) to a 3rd drive (also 2TB) which had the space to hold the total files. When it moved the files from the 2nd to the 3rd drive it had no stops at all. So perhaps the 4TB drive needs ditching, which would be a shame as it's also the newest one.

Reply
User profile for user: Richard.Taylor
Richard.Taylor
User level: Level 7
22,560 points

Jun 9, 2025 10:15 AM in response to David Bywater

David Bywater wrote: … So perhaps the 4TB drive needs ditching, which would be a shame as it's also the newest one.

It could be, but you can do other things first. You can run First Aid with the Disk Utility app. Just re-formatting it may solve the problems. If you don't need to be able to use this drive with Windows, format in APFS with Disk Utility.


You didn't say what the formats of your drives are, but to run a Photos Library, an external drive must be formatted in either APFS format or Mac OS Extended (Journaled) format. Trying to run a Library from an improperly formatted drive can damage the Library. They can be stored on drives with other formats, but not run from them.

Reply
User profile for user: Richard.Taylor
Richard.Taylor
User level: Level 7
22,560 points

Jun 9, 2025 7:28 AM in response to David Bywater

David Bywater wrote: … Not sure how I can keep that updated in future

The version you just made is the best one to continue with in the future. Can you tell which file(s) caused the problem? They may be lost forever, or you may be able to concentrate on them to fix them. But it's better to continue with the fresh error free copy than to deal with the errors later.


In any case, it seems like you should find which files didn't transfer so you have a shot at preserving them.


It's great that you got the Library to work!

Reply

This thread has been closed by the system or the community team. You may vote for any posts you find helpful, or search the Community for additional answers.

Problem backing up Photos - read write errors

Welcome to Apple Support Community
A forum where Apple customers help each other with their products. Get started with your Apple Account.
Learn more Sign up