Solve Javac IntelliJ: error:java: javactask: source release 1.6 requires target release

Click on:

File -> Settings

In the search box, search for:

Compiler

Under the compiler section, click on:

Java Compiler

Under the per-module bytecode version section:

Remove the current bytecode version by clicking on the – button

Add a new bytecode version by clicking on the + button

Select the same version the compiler complained about (v 1.6).

Below is a screenshot of the above process: