[1.9 - 1.12.2] Strange ClassNotFoundException crash in Forge development envrionment

[Choonster]

My mod shadows the Apache HTTP Client Fluent API (buildscript is here) and runs a basic test with it in postInit (see here).

 

This works fine in my mod's development environment and the release client, but for some reason it crashes with a

ClassNotFoundException

 

for a Fluent API class in the Forge development environment (where I was testing some stuff in preparation for a PR). The class is definitely present in my mod's JAR.

 

You can see the FML log from the Forge development environment here.

 

Does anyone know why this is happening?

Edited February 24, 2018 by Choonster

[BusyBeever]

Maybe there went something wrong while repacking? Is the path inside the jar correct?

[Choonster]

The class is definitely in the JAR at the right location, I can view it in a decompiler and run the same mod JAR in a fresh Forge 1.9- 12.16.0.1864-1.9 MDK or release client without crashing.

[Choonster]

I've encountered a similar issue again while testing a PR.

 

When attempting to run the Minecraft client from the Forge development environment with either JEI or TestMod3 in the mods directory, the game crashes with a ClassNotFoundException for a class that definitely exists in the corresponding mod JAR. This doesn't happen outside of the Forge development environment (neither in my TestMod3 development environment nor when launching Minecraft from the Mojang launcher).

 

This was tested using Forge 1.12.2-14.23.2.2619 (commit 49be9b2) with JEI 1.12.2-4.8.5.147 and TestMod3 1.12.2-5.1-2ce586d (in separate runs). You can view the FML logs from these runs here.

 

Does anyone have any idea why this would happen or how to fix it?

Edited February 24, 2018 by Choonster