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RapidWeaver Version: 7.0 (17706)
System Version: 10.11.5 (15F34)
Hardware: MacBook Pro (Retina, Mid 2012) 16GB DDR3.
Issue:
Whenever I try to load a RW6 project RW7 makes appear a crash dialog box
Same here. Same RW version, same OS X version but a 2014 5K iMac, 32Gb memory.
I’m using the Elixir Geometric theme if that makes a difference. Some other projects (using different themes) open OK.
I can start a new project with that theme without issue. I do have quite a few stacks in use on it. 
Could be that the theme you are using or plugins you use might not have come over to RapidWeaver 7
I’d hope that RW7 could load the project and just drop the troublesome plugin in that case though. Trying to recreate the site from scratch wouldn’t be much fun.
In my case Paragraph Pro by Big White Duck was the issue. I went back to RW6, checked for stack updates and it appeared.
I downloaded the update, saved the project and RW7 loaded it without issue. I note that it mentioned causing RW7 crashes in the beta in its release notes.
Awesome! Glad you got it all sorted out!
I love your themes by the way - looking forward to seeing what you do with RW7!
Duly purchased! 
Sweet! Thanks! Enjoy. It is a very fun theme!
