Will a photo library from High Sierra stored on an external HD be compatible with Mojave?

[flyguy5]

I have owned a Mac for about a year now and Mojave will be my first Mac OS update so I am a bit new to the process. I did have a question which some might be able to answer. I have a quite large photo library which I have copied to an external HD, the operating system in which I copied the entire photo library to the HD was High Sierra. If I upgrade to Mojave, will the High Sierra photo library file I have copied to the HD still be compatible with Mojave? If yes, will it automatically upgrade the external photo library with the new changes when it is opened for the first time after the update? If no, how do I make sure it is compatible?

 

[hallux]

My library has been with me since I got my Mac in 2012, I'm currently running High Sierra and have migrated my library from iPhoto to Photos. Unless there is a drastic change in Photos, it should be fine. If there IS a drastic change in Photos Apple will provide a migration path, and I suggest a backup of the library prior to kicking off the migration. Storage location shouldn't matter, unless that storage location is stored on a shared storage device and both Macs accessing it aren't upgraded (if Apple makes changes to the library format).

 

[Lunder89]

The photolibrary file works fine on my test mac, running the Mojave beta.

It should work without a hitch

 

[flyguy5]

The photolibrary file works fine on my test mac, running the Mojave beta.

It should work without a hitch

So just to be clear, the photo library file copied under a High Sierra to an external HD works as normal under Mojave?

 

[Lunder89]

My library didn't live on an external harddrive, but yes.