I've been using the testfor command in 15w34 to test for certain items in a player's inventory and it worked and as soon as I logged in with 15w35 I get an error. I even tried to testfor player without the tags and I get the same error. Then I tried to testfor in chat and I get the error.
The error is: invalid tag encountered, expected { as first character.
Comments 5
All the commands I used(I also tried each with my Minecraft username)
/testfor @p
/testfor @p minecraft:writable_book
/testfor @p minecraft:writable_book 0 0 {pages:["win"]}
/testfor @p should work, the others require brackets around (and you'll probably want to look at the data structure, as well).
Please provide the exact command you used.