I’ve been setting up our Mini for two users logged in at the same time (one using the Mini and the other remotely logged in via VNC). While testing this setup I encountered the following error message when opening some of of the Photos libraries on an External drive.
Library could not be opened.
The library “xxxxx” is in use by another program.
[Open other] [Quit]
After a bit of experimentation I realized that this message occurred when one user was trying to access the Photos “System Library” of the other user. It appears that Photos in Mojave “locks” each user’s ‘system library’ even when it has been closed and Photos is not active.
So I created dummy Photos “System Libraries” for each user, so that both users could access all of the Photos libraries on the external drive (20 libraries - 1.5TB).
FWIW a similar message would occur with Photos in El Capitan -- but only if the other user was actively using that library, even if it was the other user's "system library".
GetRealBro
Library could not be opened.
The library “xxxxx” is in use by another program.
[Open other] [Quit]
After a bit of experimentation I realized that this message occurred when one user was trying to access the Photos “System Library” of the other user. It appears that Photos in Mojave “locks” each user’s ‘system library’ even when it has been closed and Photos is not active.
So I created dummy Photos “System Libraries” for each user, so that both users could access all of the Photos libraries on the external drive (20 libraries - 1.5TB).
FWIW a similar message would occur with Photos in El Capitan -- but only if the other user was actively using that library, even if it was the other user's "system library".
GetRealBro