#Minecraft forge for mac 1.12 how to#
#Minecraft forge for mac 1.12 install#
#Minecraft forge for mac 1.12 mod#
#Minecraft forge for mac 1.12 full#
#Minecraft forge for mac 1.12 code#

As a result of compiling with a newer version of Xcode, this bug, which was previously lying dormant, was suddenly revealed, and the full wrath of Apple was brought down mercilessly upon anyone who just wanted to play modded Minecraft with updated, faster, and safer JDK 8 builds.

#Minecraft forge for mac 1.12 code#

The LWJGL code I hacked out is safe to run form the main thread, so LWJGL is not the issue: the issue is when and where LWJGL's native interface code is called. By toggling the ability of the game window to be resized, Forge is very likely inadvertently causing the NSWindow to be modified from a non-'main' thread (from the stack trace, the NSWindow might be updating window visuals as a result of it being resizable / non-resizable). Apparently, in older versions of MacOS's development tools, there was less stringent checks on this occurring in certain areas (I don't hate myself enough to find out more).

MacOS sort of forces developers to do all rendering / window (or NSWindow, as the crash log notes) modification related stuff in the 'main' / 'first' thread (I don't personally code native Mac applications, so I don't know much about this). So, why does this break everything? It's complicated.

A TL DR of the code is that when fullscreen is exited, Forge toggles the ability to resize the window off, and then back on again, in order to work around a LWJGL bug where the window wouldn’t have been allowed to be resized. So what broke it? By running every version of Forge for 1.12 until my game started crashing when exiting fullscreen (less of a waste of time, GraalVM is amazing), I tracked the code causing the crash down in Forge to probably being this line, introduced by this commit, to fix this bug. So, it’s a LWJGL bug, right? No, because vanilla 1.12.x Minecraft does not crash when exiting fullscreen.

#Minecraft forge for mac 1.12 how to#

You can find my very very bad hacks to make it build here, but they are not portable and will not compile outside of my laptop (though the first commit should give you a general idea of how to fix the build errors). By hacking together and compiling LWJGL 2 for newer versions of Mac's developer tools (don't do this, I wasted hours of my life trying to get it to compile) and running Forge with the resulting built native libraries (this was a huge pain, please don't bother doing this), I found that commenting out that line 'fixed' the problem (I broke other things getting it to compile).

I tracked the crash down to this exact line of code in LWJGL 2. which is the worst sort of message you can get in a Java stack trace. Libc++abi.dylib: terminating with uncaught exception of type NSException The first thing I noticed when I encountered this issue was that the crash was reported to have happened during native MacOS execution, in liblwjgl.dylib: There is a somewhat complicated cause for this issue.

#Minecraft forge for mac 1.12 mod#

Installing any mod is not required to trigger this issue, it is 100% reproducible with just Forge.

Run Forge with the newly installed JDK, enter fullscreen, then exit fullscreen.

MultiMC was used during testing for version management, but this issue was also replicated on the official launcher). or higher (these issues still occur on Forge 14. GraalVM 20.3.0 EE was used during testing, as well as AdoptOpenJDK 8u275-b01. (As proof that this is actually a XCode compilation related issue, Amazon's JDK 8 fork (Corretto 8) does not suffer from the same issues due to having a different build process which still uses Xcode 4, despite being based on the latest versions of OpenJDK (tested with Corretto 8u275)). As Oracle and the OpenJDK community have started compiling JDK releases with Xcode 10.1, this can be achieved by downloading an offical Oracle or OpenJDK build of JDK 8u261 or newer.

#Minecraft forge for mac 1.12 install#

Download a JDK compiled with a newer version of Xcode (Xcode 4.5 was used until recently), and install it on a computer running MacOS.

to the most recent releases of Forge for 1.12.x (14.).