World Deletes on updates

[Moridin]

Hi there. My problem is basically what is said in the thread name. My wife and I have been playing the Direwolf20 1.6.4 modpack for quite some time. We've modded it a little with some mods we either thought were interesting, or had wanted to play after seeing them on Forgecraft. But anyway, every time we have a joint world together, when the pack updates, half the time after the update, the world has been deleted. Its a little sad since we keep getting pretty mid-game level, and then suddenly, we have to start back at the beginning again.

Is there anything that might be causing this? Or should we just back up the world after each play and hope for the best during the next update?

Direwolf20 1.6.4 16th iteration sans Billund and Opis, and active Zans.

Additional mods:
AgentsAgriculture_1.3.5
Blood Magic v0.7.2b
ConfigMod for MC v1.6.4
CoroAI for MC v.1.6.4
DamageIndicators-1.6.4-2.9.1.6
ExtendedRenderer for MC v1.6.4
ModBuild for MC v1.6.4
Pam's Clay Spawn 1.6.4
Pam's Simple Recipes 1.6.4
PamsHarvestCraft-1.6.4-1.1.4
Reliquary-1.6.4-1.1.1
Sync2.1.1
Thaumcraft4.1.0e instead of the 16 d version.
thaumcraftmobasapects-1.6.X-1e-build2
ThaumicTinkerer-2.3-130
Tropicraftv5.1.6 Mod for MC v1.6.4
UsefulFood-1.6.2-1.4.4
Weatherv1.59 Mod for MC v1.6.4
Witchery_0-15-1_164

I don't believe this is just a recent thing with the added mods, as this was happening before with our Direwolf20 1.5 worlds. If there is any advice, or even full on help, I would appreciate it.

Thanks again,
Moridin

 

[UniZero]

We would need to see a log when the crash occurs. If you care if you lose the world then take regular backups of it.

Edit: When the pack updates the mod pack makers always say to backup your world before updating.

 

[Moridin]

Sadly, there's no crash. Its just suddenly gone. And that makes sense. I just tend to be a huge derp and forget to remind her to back it up since its on her computer.

Before asking about this, I warned her to start saving the world after every playthrough, just to be sure. Good to know I'm not just paranoid.

 

[UniZero]

If the world is still in the saves folder then try the method below to get the world working again.

http://forum.feed-the-beast.com/threads/direwolf20-1-6-4-1-0-14-world-dissapeared.40499/#post-551684