Error "java.lang.OutOfMemoryError: Java heap space" when build or debug project

Problem

When build or debug projects, IntelliJ IDE always throws "OutOfMemory" heap error. An increase of heap memory (-Xmx) doesn't help.

There is an error in idea.log:

2024-07-10 18:13:06,583 [ 262266] SEVERE - #o.j.k.i.c.KotlinCompilationStatusListener - 
Kotlin: [Internal Error] java.lang.OutOfMemoryError: Java heap space

Cause

The -Xmx controls heap memory used by the IntelliJ IDE itself. It isn't the same as the heap size for compiling your application.

If the error is regarding OutOfMemory used by your Project, you need to increase the "build process heap size".

Solution

Navigate to Settings | Build, Execution, Deployment | Compiler | Shared build process heap size (Mbytes), and increase the value of it.