error: compiler message file broken: key=compiler.err.Processor

Kotlin 2.61

A missing @Provides annotation in Module on Dagger 2.17 results in error: compiler message file broken: key=compiler.err.Processor: org.jetbrains.kotlin.kapt3.base.ProcessorWrapper@550c0cf8 arguments={0}, {1}, {2}, {3}, {4}, {5}, {6}, {7}

A missing @Provides annotation in Module on Dagger 2.15 results in a meaningful exception describing which dependency could not be provided

[simpers]

Basically the problem happens if you have a multi gradle project, and one of the gradles submodules imports something, but doesn’t expose it to the parent. (like RxJava in the example project). The kapt error occurs only if RxJava classes are used as the parameters of the methods, not when used as the return types.

I got the error because my base module had a dependency on Room but it was imported with implementation instead of api

implementation "androidx.room:room-runtime:$androidx_room_version"
⬇️ 
api "androidx.room:room-runtime:$androidx_room_version"
kapt "androidx.room:room-compiler:$androidx_room_version"

So if you end up hitting this error, double check the libraries you’re trying to access and whether those are truly imported in the right modules or “re-exported” in submodules, depending on how you setup your gradle files.

[simpers]

What’s the status on this? I’ve been struggling for a long time getting an Instant App working and now most recently I got this error, and I’m writing it in Kotlin.