Bug Report

I load up my oldest save, and it either crashes out immediately, or locks up (while still creating a log!) Oddly enough, if I switch to a different window, and switch back, it will work for about a second before crashing. I have tried different methods to fix the problem, different versions of forge, limiting RAM to the recommended 8G, and still have problems. (incidentally, my other game worlds performance has improved!) I have to completely restart the launcher each time it crashes, so any focused help problem solving is greatly appreciated!

Expected Behaviour

The world in question loads without issue, and building commences.

Possible Solution

I think the issue might be with the "welcome to Sevtech/ Getting started" screen that appears every time I load a world. Can the world load splash screen be disabled, or can someone tell me which mod creates it, so I can remove that mod and try to reload?

Steps to Reproduce (for bugs)

1. load that world,
2. crash.
   NOTE: Should I pass on the world files? All my other worlds work fine.

Logs

Pastebin link:
https://pastebin.com/ddqe2GwZ

Client Information

ALL Current Forge, Sevtech Modpack, and JAVA versions.
Some attempts to fix problems were done with this save. I was altering crafttweaker recipes to fix dyed wool, and Pink Slime Ingot creation when in version 3.1.1. Also added recipies to make Betweenlands holiday foods craftable for fun, and practice with scripting. Don't think that matters, as I am now using the current 3.1.2 script unaltered, but if something corrupted the save, it'd be nice to figure out.
I had also left a "Compact Machine" with a corrupted chorus fruit to kill a shulker that teleported outside the confines of the inside, don't know if that did anything. (other then kill the player)

Thanks for any help or information you can give.

Sorry.
Sevtech 3.1.2
Minecraft 1.12.2,
MCP 9.42
Forge 14.23.5.2838
Windows 10,
JAVA 1.8.0_51 (well, you found that out faster then me. :( Lesson learned,
8Gig RAM
Minecraft Launcher 2.1.5964 (through twitch for the fresh instance)
no optifine, shaders, or anything else that I am aware of.

There was something I forgot to add in the report, I only crash on returning to the Overworld. I had restored my game from every backup, but whatever caused the error started before my oldest backup. I can bounce around Abyssalcraft dimentions, Extra Planets, and Galacticraft planets, without issue via Avanced Ender Pearl. only when I go back to the Overworld, does it crash.

A fresh instance of 3.1.2 had the same issue. Lock up on load, but left a crash report.
https://pastebin.com/Ed5KzWWA

sk2048
this particular world was created in Sevtech 3.1.1...

I restored from a backup where I was in the Twilight Forest, threw away the shield, and jumped into the portal, to land in the same glitch, with the same error messages.
https://pastebin.com/PvxbdFEg

You say you're using all the current versions, which is useless information. People are wrong about their versions being the latest all the time, like how you say you're using the latest Java but your log says you're using the default 1.8.0_51. You could try making a fresh instance of sevtech 3.1.2, and copying your world over to see if it will load in that environment

If the crash report is reproducible, it has nothing to do with the news screen. It's crashing while handling capabilities added to shields by Twilight Forest. Perhaps a shield in your inventory has become corrupted?

It would be nice to know which version of the mod pack your world was created in?

Well, I have poked around everything I can from my end. The Twilight Forest Shield is actually based on TF achievements, and seems to be an unimplemented feature based on update tags on it's GitHub page. Other similar complaints from other TF included modpacks have the same stacktrace messages. I think the error is going through that code, but not caused by it. My error, according to the stack trace is coming from the "FMLOutboundHandler" which seems to be responsible for sending serverwide messages based on the what little of the FML code I could find. It's as if a message flag is generated but no message was created for it, which caused the NullPointerException. I can't see the code to determine what's causing the message, or what earlier error keeps it from actually generating. While I see a couple of suspects in the logs, I also haven't been able to use NBTExplorer, of MCEdit with any, ability to erase possible corrupted blocks /items.
Any extra thoughts, or pointers to tutorials on using MCEdit with modded minecraft, will be appreciated!

FML is open source, FMLOutboundHandler is responsible for sending messages both from server to specific targets and broadcasts and from client to server. OutboundTarget$9 seems to be client to server messaging, and it is possible this is somehow being reached on the server thread (Exception in server tick loop).

It does appear to take sensible precautions against a null pointer resulting from this however.

I have not had time to investigate this to the point I am prepared to give any definitive conclusions however.

For reference the source of FMLOutboundHandler is available here: https://github.com/MinecraftForge/MinecraftForge/blob/1.12.x/src/main/java/net/minecraftforge/fml/common/network/FMLOutboundHandler.java

Looks like I'm wrong about $9 referring to client to server messaging. Looking at the stack trace it seems more likely it refers to TRACKING_ENTITY.

Thanks for the pointer!

For the sake of completion, and problem solving, I've isolated the issue to a Twilight Forest map I was using for decoration. After deleting it out of it's item frame with NBTExplorer, the game runs fine, and intact! I used NBT Explorer to move the item to an empty chest, and the game crashes when I retrieve it. Other TF maps I had previously made that were in storage also crash my game. New maps created in the Twilight Forest, also kill the game. Deleting or not touching them and life is fine. I am assuming something has corrupted the map code, and that is what is creating my null pointers. I don't know if that is something I had caused while tweaking custom recipes, or a glitch I manage to trigger, but I can figure it out I will post it here.