I have created mod for 1.16.5, and it works well enough. But, when I tried to port it to 1.17, I found that MOST of minecraft classes used in mod are no longer available (event bacic ones like block, item, entity, etc.). IntelliJ IDEA marks almost every line as error. What actually happened? Is 1.17 so much incompatible? Or there was some error in workspace setup?

This is my build.gradle

 

 

Most likely it's a problem with your workspace. Can you post a picture of your Referenced Libraries? If you don't see your libraries, then first check if you have  jdk 16. Then, go to your project directory and run the command gradlew refresh, or gradlew eclipse.

Hope it helps!

forge now use mojang class & package names, thats the problem
you can se the forge bot on discord to convert the names

4 minutes ago, Luis_ST said:

forge now use mojang class & package names, thats the problem
you can se the forge bot on discord to convert the names

It seems like class name conversion goes wrong:
 

Z:\Dev\Zombienation-1.17>gradlew -PUPDATE_CLASSNAMES=true updateClassnames

> Configure project :
Java: 16.0.2 JVM: 16.0.2+7-67(Oracle Corporation) Arch: amd64
WARNING: This project is configured to use the official obfuscation mappings provided by Mojang. These mapping fall under their associated license, you should be fully aware of this license. For the latest license text, refer below, or the reference copy here: https://github.com/MinecraftForge/MCPConfig/blob/master/Mojang.md, You can hide this warning by running the `hideOfficialWarningUntilChanged` task
WARNING: (c) 2020 Microsoft Corporation. These mappings are provided "as-is" and you bear the risk of using them. You may copy and use the mappings for development purposes, but you may not redistribute the mappings complete and unmodified. Microsoft makes no warranties, express or implied, with respect to the mappings provided here.  Use and modification of this document or the source code (in any form) of Minecraft: Java Edition is governed by the Minecraft End User License Agreement available at https://account.mojang.com/documents/minecraft_eula.

> Task :extractRangeMap
java.lang.IllegalArgumentException: Could not get Binary name! com/madalchemist/zombienation/CreativeTab.java @ 223
        at net.minecraftforge.srg2source.extract.ExtractUtil.getInternalName(ExtractUtil.java:39)
        at net.minecraftforge.srg2source.extract.SymbolReferenceWalker.getInternalName(SymbolReferenceWalker.java:105)
        at net.minecraftforge.srg2source.extract.SymbolReferenceWalker.process(SymbolReferenceWalker.java:406)
        at net.minecraftforge.srg2source.extract.SymbolReferenceWalker$1.visit(SymbolReferenceWalker.java:750)
        at org.eclipse.jdt.core.dom.SimpleName.accept0(SimpleName.java:198)
        at org.eclipse.jdt.core.dom.ASTNode.accept(ASTNode.java:3055)
        at org.eclipse.jdt.core.dom.ASTNode.acceptChild(ASTNode.java:3103)
        at org.eclipse.jdt.core.dom.SimpleType.accept0(SimpleType.java:195)
        at org.eclipse.jdt.core.dom.ASTNode.accept(ASTNode.java:3055)
        at net.minecraftforge.srg2source.extract.SymbolReferenceWalker.acceptChild(SymbolReferenceWalker.java:93)
        at net.minecraftforge.srg2source.extract.SymbolReferenceWalker.process(SymbolReferenceWalker.java:544)
        at net.minecraftforge.srg2source.extract.SymbolReferenceWalker$1.visit(SymbolReferenceWalker.java:769)
        at org.eclipse.jdt.core.dom.TypeDeclaration.accept0(TypeDeclaration.java:509)
        at org.eclipse.jdt.core.dom.ASTNode.accept(ASTNode.java:3055)
        at org.eclipse.jdt.core.dom.ASTNode.acceptChildren(ASTNode.java:3126)
        at org.eclipse.jdt.core.dom.CompilationUnit.accept0(CompilationUnit.java:258)
        at org.eclipse.jdt.core.dom.ASTNode.accept(ASTNode.java:3055)
        at net.minecraftforge.srg2source.extract.SymbolReferenceWalker.safeWalk(SymbolReferenceWalker.java:81)
        at net.minecraftforge.srg2source.extract.RangeExtractor$1.acceptAST(RangeExtractor.java:234)
        at org.eclipse.jdt.core.dom.CompilationUnitResolver.resolve(CompilationUnitResolver.java:1065)
        at org.eclipse.jdt.core.dom.CompilationUnitResolver.resolve(CompilationUnitResolver.java:661)
        at org.eclipse.jdt.core.dom.ASTParser.createASTs(ASTParser.java:1001)
        at net.minecraftforge.srg2source.extract.RangeExtractor.batchGenerate(RangeExtractor.java:250)
        at net.minecraftforge.srg2source.extract.RangeExtractor.run(RangeExtractor.java:149)
        at net.minecraftforge.srg2source.RangeExtractMain.main(RangeExtractMain.java:116)
        at net.minecraftforge.srg2source.ConsoleTool$Redefined.main(ConsoleTool.java:115)
        at net.minecraftforge.srg2source.ConsoleTool.main(ConsoleTool.java:48)

(and this repeats for every class in my mod)
 

 

12 minutes ago, Justin1205 said:

Most likely it's a problem with your workspace. Can you post a picture of your Referenced Libraries? If you don't see your libraries, then first check if you have  jdk 16. Then, go to your project directory and run the command gradlew refresh, or gradlew eclipse.

Hope it helps!

I see libraries, including forge, but cannot find required classes inside