IntellijJ IDEA: Maven home directory is invalid

When creating a new project based on Maven archetype, IntelliJ IDEA wants to know certain Maven-related directories. It took a few minutes to figure out what IDEA actually wants here, and answering incorrectly gives the not very informative “Maven home directory is invalid” error message.

The Maven home directory is the place where your Maven installation is located. It is not your personal Maven directory, which in Windows is usually c:\users\<username>\.m2

The “Maven home directory is invalid” message would be a lot more helpful if IDEA would tell WHY it thinks the directory is not valid. If you are trying to find a specific file or subdirectory - please tell me.