I’ve received a number of requests from people asking how I fix these maps, either out of curiosity, or because the problem (crashing computers, laptop batteries) happens often they don’t want to submit a map every week.
I will flesh out this section more soon, but here are the basics.
First and foremost, before fixing anything. BACK UP YOUR SAVE FILES. I can’t stress this enough, and chances are this website would be obsolete if there was an easier backup method (or if saves didn’t go corrupt in the first place >.>).
Before attempting to fix any map, I first test it in it’s original state to verify the problem, be it not loading, frozen in place, or anything else.
The next step is to check for bad chunks. I use MCEdit to find these. DO NOT RUN MINECRAFT WHILE MCEDIT IS RUNNING.
(EDIT: Chunkster no longer works for 1.2. It only works for 1.1 and below)
Lets start with the most common problems.
Minecraft Save Doesn’t Show Up In Minecraft Loader
Cause: Usually minecraft or the computer crashing while the game is running.
Problem: The level.dat, which holds pretty much all of the game data that isn’t the map itself, becomes corrupt.
Fix!: MCEdit no longer automatically fixes broken worlds as of 1.2. You will need to create a new world with a DIFFERENT name than the broken one. If you used a seed name/number, use that now. Also make the same settings of Normal/Flat and Survival/Creative. Create that world, exit it, exit minecraft. Now drag the level.dat from the NEW world, into the save folder of the OLD world. This will replace it, and hopefully allow you to enter the old one.
World Loads, But Frozen In Place -OR- Giant Hole Through World -OR- A Billion Pigs/Creepers/Chickens/Etc Spawned! -OR- World starts to load, but immediately goes to “Saving Chunks” and crashes
Cause: Bad chunks. I don’t know what causes the bad chunks specifically, but it is a bad chunk issue.
Problem: When a chunk (a 16×16 block area from bedrock to sky) fails, it simply disappears. However that area is still mapped, and causes data problems. This can range from just a weird hole in the ground, to lag, to causing you, and all nearby things (mobs included) to freeze in place, or even causing literally thousands of mobs to spawn instantly. You can still look around and interact with stuff within reach, but that’s it. Sometimes makes screen jiggle too.
Fix!: (EDIT: I used to use Chunkster. This tool no longer works for 1.2, and it is MUCH more difficult to find and remove bad chunks). I use MCEdit, open the world, go to World Info, and click Repair Regions. Unfortunately, the newest version of MCEdit wont show you if there are bad chunks, and if they were removed. I use version 0.1.0.1, which DOES display that information. Usually you will have to navigate to that place on the map in MCEdit and then delete it manually. I would honestly just recommend sending the maps to me if this was the case. Those chunks will regenerate once the game is loaded with natural landforms. MCEdit is also used to remove the mobs (entities) from the map, if a large quantity was created.
A note! Sometimes Chunkster will come up with odd errors that it can’t seem to resolve (like this) no matter how many times you run it. Don’t worry! It’s still just a bad chunk, it’s just being fiesty. You’ll need to go into MCEdit and eyeball the bad chunk (it will be an empty square chunk). When you mouse over it, your MCEdit log will probably start to totally flip out, with hundreds of lines of errors. Just select the chunk, delete it, and all should return to normal. Save n quit.
Opening or Breaking Chests Causes Game to Crash
Cause: Items the game doesn’t support due to mods that are outdated/broken/uninstalled
Problem: The game is designed with specific items. If a mod is used to add a new item (Lets say, Obsidian Tools), the game will work with the mod. If the mod is removed or the game updated without the mod, the game no longer understands how to process that item. As soon as it needs to ‘do’ something with the item (either look at it, or have it pop out of a chest), it blerks.
Fix!: This can be tricky. The simplest method is to use MCEdit and simply delete the chest with the offending items. Unfortunately, that will also delete any other items in the chest, regardless of their nature. The other option, if it’s possible, is to reinstall the mod long enough to remove and destroy the items, and then remove the mod again.
My Biome Changed OR Ice Is Spawning Everywhere
Cause: The map seed has changed, in turn changing biomes and terrain generation
Problem: Terrain generation is determined by the seed, as is biome location and weather. If you start with (for example) seed 555, play for a while, and the seed changes to 777, all terrain generated after that will be based off 777. ALL biome areas will also change, which may dump a ton of snow on your grassy home. Or the opposite! Seeds can change for a number of reasons, including game crashes. Servers (in my experience) seem to do it a lot more for no explainable reason.
Fix!: This one cannot always be fixed. The only way to resolve this issue is to have the original seed the world was based off of. If you have a backup of your world, it may have the old seed. If you made the map after 1.3, and used a name to create the seed, you can recreate a new world (after backing up and moving your current one!), and find the seed number that way. Lastly, sometimes for servers the seed may be listed in the server.properties file, and you can get it that way. If you have the original seed, you can download NBTEdit and change the seed number in the level.dat file, and that should resolve it.
I Cant Die OR I Start Dead Immediately
Cause: Incorrect health/armor values
Problem: The game recognized up to 20 health (2 health per heart). Any more health than 20 still looks like 20. Sometimes level.dat corruption or mods that give you ‘invicibility’ are installed or uninstalled wrong, or simply are poorly designed. This may leave your character with a massive amount of health (usually in the thousands). It looks like invincibility because knocking out 6000 health takes forever, just about, and it will always look like 20 in game. Likewise, always starting dead has a negative value, or some other oddity in character info in the level.dat.
Fix!: Easy one! Use NBTEdit, open the level.dat, set health to 20. Also make sure nothing else is odd in there as well, or have huge/negative numbers.