unable to open pre-sierra photos library
updated MacBook pro from el capitan to sierra. now unable to open photos library - have blank photos window and revolving cursor - no messages just continues endlessly.
also have iMac which is still on el capitan and can access the library no problem.
photos library sitting on NAS accessible to both macs. from both devices I can see the photos library in finder on the NAS device.
if this an 'indexing process' for the new version of photos under Sierra and if so what's the eta to completion (my library is around 40gb of photos and some movies). and if so how rubbish is this!
any help/advice very welcome.
MacBook Pro (Retina, 15-inch, Late 2013), macOS Sierra (10.12)