Here's the code that sees if there's a book called Keys in the item frame.
/testfor @e[type=ItemFrame,r=10] {Item:{id:minecraft:writable_book,tag:{display:{Name:"Keys"}}}}
When I put this in I get the error:
[18:09:28] entity.ItemFrame.name did not match the required data structure
Can someone help fix my command?
Found entity.ItemFrame.name
(because the item frame itself doesn't have a name). Do you have other item frames nearby?/testfor
(and some other commands) because you're trying to match data tags. I see the same error you're seeing when I have a second item frame with something else in it.stats
or a comparator, but the command block's output window (which only stores 1 output line) may be overwritten if the one that doesn't match is tested second.