I cannot access my iphoto library on external hdd?

Option 1

Back Up and try rebuild the library: hold down the command and option (or alt) keys while launching iPhoto. Use the resulting dialogue to rebuild. Choose to Repair Database. If that doesn't help, then try again, this time using Rebuild Database.

If that fails:

Option 2

Download iPhoto Library Manager and use its rebuild function. (In early versions of Library Manager it's the File -> Rebuild command. In later versions it's under the Library menu.)

This will create an entirely new library. It will then copy (or try to) your photos and all the associated metadata and versions to this new Library, and arrange it as close as it can to what you had in the damaged Library. It does this based on information it finds in the iPhoto sharing mechanism - but that means that things not shared won't be there, so no slideshows, books or calendars, for instance - but it should get all your events, albums and keywords, faces and places back.

Because this process creates an entirely new library and leaves your old one untouched, it is non-destructive, and if you're not happy with the results you can simply return to your old one.

Regards

TD

please explain this statement

manually transferred my macbook pro photos (from the masters file in iphoto) to the iphoto on the external hdd.

It sounds like you used the finder to move photos into the masters folder - you must NEVER make any changes to the structure or content of the iPhoto library using the finder - if this is what thou did you have corrupted your library and need to either rebuild or restore your backup from before you did this

LN

I did not alter the structure of the photos on the macbook pro or desktop. I copied the original photos from the masters files - i.e., selected them then dragged and dropped the files into iphoto on the external hdd.

What exactly did you do? It still sounds like you moved photos into the masters folder of the iPhoto library on the external drive - if you did that is changing the content of the iPhoto library using the finder and will not work and will cause problems

LN

Sorry but I am still not clear - but in any case what happens wen you try TDs two suggestions?

LN

I suggest you do the following:

1 - plug the EHD into the desktop Mac and drag the library again to the EHD replacing the library that's there.

2 - plug the EHD into your MBP.

3 - get the paid version of iPhoto Library Manager and use it to merge the library on the MBP into the library on the EHD. This will preserve the edited versions, keywords, places and faces from the MBP library.