Q: Can't create aperture folders.

Folders will be created relative to the library item you are currently viewing. Make sure you have no folder, project, book, etc. selected, when you are using the command "File > New > Folder".

Regards

Léonie

I've also run into this exact issue on 3.4.5 almost seems to be a hard limit of some sort and things have since gone from bad to worse.  I can still create albums but no folders or projects. If I delete a folder, I can then add a new one, but I just did this and the new folder got pre-populated with a selection of photo's from "Folder A" - did an edit undo and the folder went away along with all the photos that were originally in "Folder A" - Yikes!  Nothing in the trash, zip nada - guess I'll have to restore the entire library from Time Machine.  What a mess!

I would try repairing, and if needed, rebuilding, your Library.  The TM back-up is likely to have the same problem.

Instructions are on this Apple support page.

Thanks Kirby, I actually found those same instructions and run the repair permissions and data base earlier today which seemed to fix the issue of not being able to create new folders or projects.  Alas, not even rebuilding the data base located my missing project (containing my wedding picutures!).  Ended up restoring the entire library via TM from night prior and exported my missing project as a library and importing back into the original library as I'd made some considerable changes since last night (also run repair once more after the import).

Bottom line everything seems to be working great again, and to answer the OP's question - try repairing the permissions and database as Kirby also said.

I'm having the same problem in Aperture, and very unhappy about it. There is no error message from the software. I am not happy to have such important personal files, my photo albums, be subject to wholesale disappearance without any type of warning.