When kapt complains, that it can't find a

tools.jar

(which is correct, because I'm not using Java 8 anymore) – what doesn't work then? Any way to suppress that warning (I'm using Maven)?

Hi! Can you please share full warning message?. Also, do you build your project via JPS or via “delegate to Maven”?

I'm using Maven on the command line. Full message:

[INFO] --- kotlin-maven-plugin:1.5.0:kapt (kapt) @ simulator ---
[WARNING] 'tools.jar' was not found, kapt may work unreliably
[INFO] Applied plugin: 'spring'
WARNING: An illegal reflective access operation has occurred
WARNING: Illegal reflective access by org.jetbrains.kotlin.kapt3.base.javac.KaptJavaFileManager (file:/home/hho/.m2/repository/org/jetbrains/kotlin/kotlin-annotation-processing-maven/1.5.0/kotlin-annotation-processing-maven-1.5.0.jar) to method com.sun.tools.javac.file.BaseFileManager.handleOption(com.sun.tools.javac.main.Option,java.lang.String)
WARNING: Please consider reporting this to the maintainers of org.jetbrains.kotlin.kapt3.base.javac.KaptJavaFileManager
WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
WARNING: All illegal access operations will be denied in a future release

Thank you, I’ll take a lookloading

Nice to see that this is considered for fixing. What I find more troubling is that when using AdoptOpenJDK 16, the (deprecated) switch

-Dillegal-access=permit

has to be set in order for kapt to work. This means that kapt will cease to work with JDK 17, 18 or whenever that option will be removed.