Minecraft: 1.11.2
Buildcraft** version: 7.99.8.1
Forge** version: 13.20.1.2530
Link to crashreport : https://pastebin.com/yVdjL2Fw
Singleplayer/multiplayer: Multiplayer, but this only crashes clients, the server is unaffected

Happens far more in 1.12.2.

I've had it happen when joining the game and happen when using conflicting commands when GUIs open.

For example if you bind the extra utils inventory search feature with T it will crash the game because of this mod.

You can also use this crash to dupe any block in the game if you have carry on installed so it should probably be fixed ASAP.

if another mod is causing dupe's as a result of the game crashing you wana report that to that mod as that mod is probably doing something funky then

it's crashing cause somehow a null blockstate is being written to NBT, seems like some mod is managing to get past earlier safety checks yet return null there, if you could narow down the mod (or even block(s)) causing this it would help a lot

@AlexIIL could you maybe add some aditional safety checks at that points to stop it from crashing but log what block is misbehaving?

@Shiz0id and @HorizonsMC, can you retry with this testing jar: 7.99.13-pre2?

Update, pre-2 has been uploaded as pre-1 didn't work quite right.

Unable to test with current mods on 1.12.2 because of this crash.

https://pastebin.com/5jW6HwPZ

Thanks for testing - I should probably have mentioned, but I moved the test code to post-init so that it would crash quickly than waiting for a creative tab to be opened. I've uploaded 7.99.13-pre3 to fix the first crash (looks like some tests broke immediately)

Actually it looks like I made a mistake in pre-3: please don't test it quite yet, its broken.

New crash: https://pastebin.com/Vb4et2v1

Edit Sorry posted before I saw your new post.

Thanks. That's odd, I'll do some testing with forestry for a bit...

I removed forestry and all my bee mods and it gave me the same error with extrautils on a different block so I don't think it's a Forestry issues specifically. Edit: It happens without foamix and on the server too so it's not an issue with a client side mod incompatibility.

Everything I am using is the latest version of the mod and Forge is the latest version (14.23.1.2559)

Edit 2: removed Extra Utils and now it's a tech reborn block causing it: https://pastebin.com/nXakEWqP

Edit 3: Successful boot with these mods removed.
https://i.imgur.com/1AWGGGH.png

Edit 4:
Narrowed the mods causing it down to having any one of these loaded.
extrautils2-1.12-1.6.8
forestry_1.12.2-5.7.0.214
TechReborn-1.12.2-2.10.0.364-universal

Ok here's pre-4, which doesn't seem to be crashing with forestry or extra utils any-more. although it has a lot of log spam with nonconforming properties.

Build loads on the client, crashes on server. https://pastebin.com/7E4ERSmk

Edit: It loads with ExtraUtils disabled.

Good news is it appears the GUI crash is fixed 👍

I am unable to test with Extrautils ATM due to the crash cause I was able to get it to crash with that too.

Edit 2:

Potential conflict with Cyclic? IDK if it's supposed to be called that.
https://i.imgur.com/1mSpGng.png

Ok, looks like extra utils wasn't ported quite carefully enough (the method "IProperty.parseValue" used to be client side only, however in newer versions it was changed to be on the server as well), and it looks like @rwtema didn't spot that small change. Unfortunately it doesn't look like he'll be back anytime soon.

Anyway to skirt around the issue, or will buildcraft be incompatible with EXU2 till they can fix the mistake?

@HorizonsMC it means that you won't be able to make any facades from extra utils blocks. Edit: actually, that means that there's still more for me to work around.

@AEnterprise possibly a slightly different issue, I think I'll need to look into it a bit more.

since the first report he generated pointed at forestry does that mean the same issue is present there?

alright, just making sure there aren't any issues in other mods that should be forwarded

It likely will need to be, I just want to make sure that IProperty.getName(value) is actually meant to mirror IProperty.parseValue(name), and its actually a big issue if they don't.

@HorizonsMC Thanks for the heads up with locale names conflicting - although note that I don't get notifications on edits, so I might have missed that :/

In theory all crashes should now be fixed in 7.99.13-pre5

Sorry for the late reply, just grabbed 7.99.13-pre8 and it's giving a new crash on both client and server.

https://pastebin.com/uZpu3zTZ

That's fixed by TheCBProject/CodeChickenLib#119. (Hopefully they pull it and release it soonish)

Okay, got CodeChickenLib-1.12-3.1.4.327-universal which should have the fix for the old crash, I'm running 7.99.13-pre9 and here is a new crash with Integrated Dynamics.

https://pastebin.com/8fmwwgap

Update: Removed Integrated Dynamics and Integrated Tunnels and I was able to load up on the client and server.

Good news is the new crash I found when opening an Advance Rocketry GUI is fixed in the dev builds.

I should probably have already linked the PR but that was fixed by CyclopsMC/IntegratedDynamics#442

I'm using 7.99.12 in my curseforge pack and got this error on the client side. It happens when you use the creative search button.

client crash report: https://gist.github.com/kreezxil/fa711dbebbe722a6e42893cde1360108

@kreezxil Can you retry with 7.99.13-pre10?

sounds like this was #3990 and thus should be fixed? also no reply for a long time

if this does heapen again let us know