Troubleshooting

Each page names the error, says why it happens and gives the fix, with a link to the official source.

Problem	Page
@Mixin target ... was not found, or Critical injection failure: ... could not find any targets matching	Mixin target not found
Gradle can’t find the right Java, or the mod compiles for the wrong one	Wrong Java version
The build fails on Java 25 (Minecraft 26.1 and newer)	Gradle is too old for Java 25
Gradle won’t sync after a version change	Gradle sync fails after a version change
A dependency or fabric id breaks on 26.1	Old mods and dependencies on 26.1
Fabric: the access widener or class tweaker does nothing	Access widener or class tweaker
NeoForge or Forge: the access transformer does nothing	Access transformer not applied