Resolve build problems

Check tools and project selection

Check synchronization and the JDK in IDEA's MCFPP tool window. In a terminal, run:

mcfpp --version
mcfpp --project ./hello build

Java MNI uses JDK 21. Select it through MCFPP_JAVA_HOME or IDEA settings. Source links in the console open the affected line.

Kotlin reflection in a single JAR

The current minimized development JAR reports KotlinReflectionNotSupportedError for some generic NBT calls. A complete CLI runtime needs a matching kotlin-reflect library in lib.

Use the full distribution's launcher. For a manual launch, include the CLI JAR and matching reflection library in the classpath. The current build uses Kotlin 1.9.20.

This Windows example assumes mcfpp-cli.jar and lib/kotlin-reflect-1.9.20.jar in the current directory:

java -cp "mcfpp-cli.jar;lib/kotlin-reflect-1.9.20.jar" top.mcfpp.MCFPPKt build

Linux and macOS use a colon between classpath entries:

java -cp "mcfpp-cli.jar:lib/kotlin-reflect-1.9.20.jar" top.mcfpp.MCFPPKt build

This is a distribution dependency issue. Keep source declarations in the form shown under NBT address references.

Lockfiles and cached dependencies

After dependency declarations change, run mcfpp install to update locks. Run mcfpp update to select newer versions within declared ranges.

Prepare dependencies online before an offline build. --offline needs the required Gradle distribution and Java dependencies in the local cache.