Information: A user of the modpack "The Ferret Buisness" has reported a random crash to desktop when playing for a few hours. we have suggested updating to the latest BQ core, but no change. no other user has reported issues. The quotes are from the TFB discord chat (Link https://discord.gg/0sSRBJTxlwED9pTZ)
The user's name on the discord is InThayne.

Quotes:
"Not a devastating crash, just CTD every couple hours or so from a ticking player. Not carrying either quest book and not in the BQ menus during the crash." - InThayne
"The crashes have occurred as SSP although the world does get opened to LAN quite often" - InThayne
"Ugh, still eliciting the CTD. Crash logs very similar. Oh I should mention they are occurring during RF submission quests. Will turn that off and see how long she lasts." - InThayne
"I turned off RF submissions yesterday, still crashing with about the same regularity." - InThayne

Link to Crashlog: http://pastebin.com/ZBKRQ46C

-- System Details --
Details:
Minecraft Version: 1.7.10
Operating System: Windows 10 (amd64) version 10.0
Java Version: 1.8.0_91, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation

Mmm, it looks like if another thread from the network stack calls readJson and clears the objectives while writeJson is still chugging along, you'll wind up with a concurrent modification exception. consider changing objectives to ConcurrentHashMap ?

Is there any additional info needed on this?

This issue is also related to #25 which I've just posted a legacy update for