When I enter the game with Forge, the error appears, without forge the game works normally My Game Version Is 1.17

[OomarSy]

[OomarSy]

[Luis_ST]

  On 7/24/2021 at 8:16 AM, diesieben07 said:

Post the debug.log.

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not as an screenshot

[OomarSy]

20:38:52.071

game

at MC-BOOTSTRAP/fmlloader@1.17.1-37.0.5/net.minecraftforge.fml.loading.targets.CommonClientLaunchHandler.lambda$launchService$0(CommonClientLaunchHandler.java:45)

20:38:52.071

game

at MC-BOOTSTRAP/cpw.mods.modlauncher@9.0.7/cpw.mods.modlauncher.LaunchServiceHandlerDecorator.launch(LaunchServiceHandlerDecorator.java:37)

20:38:52.071

game

... 7 more

20:38:52.071

game

Caused by: java.lang.RuntimeException: java.lang.IllegalAccessError: class net.minecraftforge.registries.GameData$ClearableObjectIntIdentityMap tried to access private field net.minecraft.core.IdMapper.f_122654_ (net.minecraftforge.registries.GameData$ClearableObjectIntIdentityMap is in module forge@37.0.5 of loader 'TRANSFORMER' @6bfdb014; net.minecraft.core.IdMapper is in module minecraft@1.17.1 of loader 'TRANSFORMER' @6bfdb014)

20:38:52.071

game

at MC-BOOTSTRAP/fmlloader@1.17.1-37.0.5/net.minecraftforge.fml.loading.BackgroundWaiter.runAndTick(BackgroundWaiter.java:43)

20:38:52.071

game

at TRANSFORMER/minecraft@1.17.1/net.minecraft.client.main.Main.main(Main.java:125)

20:38:52.071

game

... 13 more

20:38:52.078

game

Caused by: java.lang.IllegalAccessError: class net.minecraftforge.registries.GameData$ClearableObjectIntIdentityMap tried to access private field net.minecraft.core.IdMapper.f_122654_ (net.minecraftforge.registries.GameData$ClearableObjectIntIdentityMap is in module forge@37.0.5 of loader 'TRANSFORMER' @6bfdb014; net.minecraft.core.IdMapper is in module minecraft@1.17.1 of loader 'TRANSFORMER' @6bfdb014)

20:38:52.116

game

at TRANSFORMER/forge@37.0.5/net.minecraftforge.registries.GameData$ClearableObjectIntIdentityMap.clear(GameData.java:418)

20:38:52.116

game

at TRANSFORMER/forge@37.0.5/net.minecraftforge.registries.GameData$BlockCallbacks.onClear(GameData.java:471)

20:38:52.116

game

at TRANSFORMER/forge@37.0.5/net.minecraftforge.registries.ForgeRegistry.sync(ForgeRegistry.java:539)

20:38:52.116

game

at TRANSFORMER/forge@37.0.5/net.minecraftforge.registries.GameData.loadRegistry(GameData.java:695)

20:38:52.116

game

at TRANSFORMER/forge@37.0.5/net.minecraftforge.registries.GameData.vanillaSnapshot(GameData.java:269)

20:38:52.117

game

at TRANSFORMER/minecraft@1.17.1/net.minecraft.server.Bootstrap.m_135870_(Bootstrap.java:53)

20:38:52.117

game

at TRANSFORMER/minecraft@1.17.1/net.minecraft.client.main.Main.lambda$main$0(Main.java:125)

20:38:52.117

game

at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515)

20:38:52.117

game

at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)

20:38:52.117

game

at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1130)

20:38:52.117

game

at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:630)

20:38:52.117

game

at java.base/java.lang.Thread.run(Thread.java:831)

20:38:54.572

monitor

Process Monitor

Process crashed with exit code 1

[C47UM X]

I have been reading other forum posts similar to this and one, has narrowed it down to the extracted version of optifine. This has happened to me, and I’m no expert but I think if you play with a different mod until the issue fixes, it will work.

[Luis_ST]

  On 7/24/2021 at 7:38 PM, C47UM X said:

I have been reading other forum posts similar to this and one, has narrowed it down to the extracted version of optifine. This has happened to me, and I’m no expert but I think if you play with a different mod until the issue fixes, it will work.

Expand  

should be the problem!
quote by diesieben07: "Optifine is not at all compatible with Forge on 1.17 yet."

[Baggytrousers27]

So what do we do if we get the same or a similar error and don't use optifine?

Output log

[C47UM X]

Well, I just switched to the Optifine launcher installation until the issue gets resolved, and update to the latest version of forge and try it every once in a while, but can you post your mods folder as a screenshot so I can compare?

 

[ZalfFX]

I had the exact same error with my mod. The error resolved when I updated the mods.toml file.

[DaemonUmbra]

  On 7/31/2021 at 8:35 PM, C47UM X said:

Well, I just switched to the Optifine launcher installation until the issue gets resolved, and update to the latest version of forge and try it every once in a while

Expand  

It's not a Forge update that's needed... it's an Optifine update...
An open-source project and closed-source project are incompatible with each other, why do you assume its the open-source project's responsibility to fix that?