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The largest change - the 'system' table that holds all your device data (IP, name, manufacturer, model, et al) is now called the 'devices' table. Much more intuitive and something I've been meaning to do for years. For those upgrading - your queries, summaries, and widgets (et al) will be upgraded as best we can. I would suggest checking any self-created items to ensure they work as intended. Also for upgraders, we have implemented a 'view' in the database named 'system' which should function as the system table did before and enable a (relatively) painless transition. That view will not exist for new installs. 
And related to that, all collections that have default items (think groups, queries, roles, et al) now have the ability to "Reset to Default". Using that function will remove any existing items in the collection and import the new items as per v5.0.0.
Changed Collections
We have removed a few items that were surplus to needs and to be frank, creating unnecessary complexity. Buildings, Floors, Rooms, and Rows are all gone. Those attributes were used only by the Racks collection and the attributes are now stored directly in the Racks table. When you create a new rack you can select an existing building, floor, room, and row or create a new one. Your existing data will populate the racks table as you would expect. 
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