IntelliJ: Error:java: error: release version 5 not supported

Question

See https://stackoverflow.com/a/12900859/104891.

First of all, set the language level/release versions in pom.xml like that:

<properties>
  <maven.compiler.source>1.8</maven.compiler.source>
  <maven.compiler.target>1.8</maven.compiler.target>
</properties>

Maven sets the default to 1.5 otherwise. You will also need to include the maven-compiler-plugin if you haven’t already:

<dependency>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-compiler-plugin</artifactId>
  <version>3.8.1</version>
</dependency>

Also, try to change the Java version in each of these places:

File -> Project structure -> Project -> Project SDK -> 11.

File -> Project structure -> Project -> Project language level -> 11.

File -> Project structure -> Project -> Modules -> -> Sources –> 11

In project -> ctrl + alt + s -> Build, Execution, Deployment -> Compiler -> Java Compiler -> Project bytecode version -> 11

In project -> ctrl + alt + s -> Build, Execution, Deployment -> Compiler -> Java Compiler -> Module -> 1.11.