I run MultiMC with JVM 8 on an Acer Aspire running 64-bit Ubuntu (v14.04).
So roughly eight months ago, I started curating modpacks for myself and a few of my buddies, and about a month and a half ago, my computer started losing worlds. It didn't matter if they were from vanilla, or any of my modpacks or anything else. Worlds started dropping like flies, and to make matters worse, I still have about 95% of the save data for each of the worlds I lost, but they won't show up in my SP world list. I've tried reverting to a previous version of the world by copypasting my backup data of the world into the instance folder, but I had no luck with that.
What I need from you, the community is to look at my error log and see if I've missed anything that may help me. I would like to be able to fix this problem without wiping and reloading this computer, but it seems that this is my only option at this point.
The pastebin file where I have dumped the error log can be found at http://pastebin.com/raw/SWPf1zvG