how to safely migrate iPhoto library to Photos app on external hard drive

Photos will create the migrated Photos Library on the same volume as the original iPhoto Library, provided the external volume is correctly formatted and compatible with Photos. You do not need to move the library to your system volume.

The external volume must not have been used by Time Machine, and it must be locally mounted (not accessed over a network). The file system format should be MacOS Extended (Journaled) or APFS.

Follow the procedure outlined here: Move your Photos library to save space on your Mac - Apple Support

If you cannot enable the "Ignore Ownership on this Volume" flag, the volume is not suitable for hosting a Photos Library.

• To migrate the iPhoto Library on the external volume quit Photos, if it is running.
• Launch Photos again while holding down the options key ⌥, until the Library Chooser dialog appears.
• Select the iPhoto Library.

First, while you can still run iPhoto on your libraries I'd run iPhoto First Aid on all of them with the following two:

1 - Repair Permissions

2 - Rebuild Database

Next read the following user tip:

Notes on Migrating an iPhoto Library from iPhoto to Photos for Mac

If you have any projects in progress I recommend you finish them before upgrading to Catalina and Photos. You can still order books with iPhoto as follows:

Hold down the Option key and click on the Buy Book button.  That will give you a PDF file that is the same as was uploaded to Apple when they were still offering print services.

 If so there's a 3rd party book provider which used to do the printing for Apple as a sub-contractor, Mimeo, that will take PDF files created by iPhoto and Photos and print and bind books and calendars. 

Also you can upload the PDF file to PrestoPhotos which can also print and bind books and calendars from iPhoto or Photos pdf files.  They've been doing it for some time now.  

Use the PrestoPhotos or Mimeo links above for direct access to the PDF file uploading and book/calendar ordering page for each site. 

You won't be able to once you convert to Photos.

Once you have the iPhoto libraries fixed and migrated to Photos you can join those libraries together with the paid version of PowerPhotos. This PowerPhotos tutorial describes how: Merging libraries



I'll start with the first question we always ask about external drives. Are they formatted correctly (APFS or MacOS extended) as shown here?

https://support.apple.com/en-gb/HT201517

If not I would not attempt the migration until they are stored on a correctly formatted drive.

In any case you will not be able to merge your separate Iphotos libraries into one photos library - you can only convert them individually.

Tony is correct that it is very important that your drives are correctly formatted.

Apple does provide an upgrader for converting libraries:

https://support.apple.com/en-us/HT202358

The article is a few years old so I am not sure whether it runs on the latest OS. You shouldn't need to copy the libraries onto your Macbook Pro. When I upgrading my library previously it just created the new Photos library on the same drive as the existing library so make sure you have plenty of room. If you upgrade the library on an external drive (not a NAS) then the upgrade process will be slower of course than if the library was on the laptop.

Russ New Boy wrote:

Apple does provide an upgrader for converting libraries:

https://support.apple.com/en-us/HT202358

The article is a few years old so I am not sure whether it runs on the latest OS.

It does not run on Catalina.

You're welcome, Gus. Good Luck. 😊