My old backup photos won’t import to current photos library on iMac

It sounds like you may be using Time Machine, is that right? With Time Machine you can, indeed, drag files from the Data folder to your Mac, but that doesn't work with a Photos Library and some other special packages-- those are rather more complicated structures. For that you need to Restore the Photos Library package.

If you open the Time Machine volume, you see "Enter Time Machine"

which gives you this display:

You can navigate to the date you want, select the Photos Library, and then choose "Restore." You'll be asked if you want to replace the current version or keep both. Keeping both might require a lot of storage.

Does this do what you need?

RhondaFly wrote: …I don't think this is Time Machine.

Here is a Time Machine drive of mine:

Yours is 5 years older, so there are differences.

If I open one of those folders and navigate to the Pictures folder,

I see my Photos Libraries. (I have several.) This is NOT a complete Photos Library package, and you can't drag it to a Mac and have it work. You have to use Enter Time Machine to get a functional copy.

Unfortunately, yours does not say "Enter Time Machine," and I'm not sure why. Just as good is to directly to the Time Machine.app in the Applications folder. When you run that, I hope, you should get the cool "going back in time" display I showed earlier. Then you can pick a date and restore the Library to your current Pictures folder.

Photos can't immediately run an old Library, but if you double click on it, Photos should update it to be compatible.

You can use File>Import to import the pictures from that Library, but they won't have albums and folders-- just the pictures. If you want the full album structure, you need to use trusted 3rd party app PowerPhotos ($35) 

Does all this make sense?

How was the back up made? Was the recovery done as per the instructions of the backup app?

What version of Photos made that recovered library? Current versions of Photos re unable to import older libraries but they can import from libraries.

Perhaps the merge function on an app like PowerPhotos may help:

https://www.fatcatsoftware.com/powerphotos/

It won't erase your previous stuff. And, While Time Machine is mostly automatic, but you can control it in System Settings>General>Time Machine. You can read about it here:

Back up your Mac with Time Machine - Apple Support

It says:

Time Machine automatically makes hourly backups for the past 24 hours, daily backups for the past month, and weekly backups for all previous months. The oldest backups are deleted when your backup disk is full.

So after a day, it keeps only one of the previous hourly backups, and after a month it keeps only one of the backups of each previous week. It's pretty clever.

Using File>Import to load the pictures from one Library to another will keep all the metadata. It doesn't change the original Library, so that is there as a backup.

I actually use two drives for backups, sort of every other day (or really, when I remember.) I also periodically drag a copy of my entire Photos Library to another drive as a third backup. I just had two drives that I was using to back each other up, both fail. Luckily, I have other backups.

You won't be able to import the library without restoring it to your boot drive with Time Machine.

To see if you can restore the library from the old Time Machine drive hold down the option key (with the old TM drive connected to your iMac and select "Browse Other Backup Discs¬" from the TM menu.

The locate and restore the library. You may have to select "Keep Both" from the menu that pops up if the restored library has the same name as your current library:

You may not want to use Photos to migrate the restored library into your current library if you have a lot or organizational effort in the old library. You may want to use the paid version of PowerPhotos. Here is a comparison between PowerPhotos and Photos:

I ran a number of tests with a 3119 photo, 72 video and 97 keyword Photos library with keywords, captions, keywords and locations.  I merged it into an empty library using Photos and PowerPhotos.  This is what I found was imported by each;

PowerPhotos:           Photos:

Albums***                                           -----------

Smart Albums (as regular albums)** -----------

Captions                                             Captions

Titles                                                   Titles

Keywords* Keywords (some but not all in tests)

Original images                                  Original images

Edited images                                     Edited images

Loctions                                         Locations

Favorites                                             Favorites

Can detect and exclude                      Duplicates

duplicates upon import or not

Neither method could import/merge projects. 

Both methods could import older iPhoto libraries into a Photos library when the iPhoto library couldn't be migrated into a Photos library. 

*The Photos app only imported 84 keywords our of 97. PowerPhotos merged 147 keywords, some which apparently were in the images but not read by Photos at the time of import or keywords delete along with photos but not purged from the database.

**The original library had 90 Smart Albums. All were merged by PowerPhotos but, as indicated above, the Smart albums were brought over as regular albums. No album of any kind were imported by Photos.

***The original library had 34 regular albums and 1 folder with some nested albums. PowerPhotos merger all of them successfully.

The original library had 72 videos. Photos imported only 57. PowerPhoto got all 72 in its merge.

Can you see a preview (select and hit the space-bar for a large picture?)

Can you go into Edit Mode (select and hit Return?)

Doing another repair (close Photos and re-launch by option-command-clicking the app icon) may help.

Does "Show Referenced Folder" appear in the file menu?

Appropriately, it's grayed out for most people. How about for you?

When give the following options be sure to select "Keep Both" or rename your current library to something unique: