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

I'm using IntelliJ IDEA Ultimate 2019.3.1. Whenever I try to start any simple Java Maven project (may it be even a simple Hello World) I get the following error:

Error:java: error: release version 5 not supported

Running java --version by terminal I get the following output:

openjdk 11.0.5 2019-10-15
OpenJDK Runtime Environment (build 11.0.5+10-post-Ubuntu-0ubuntu1.1)
OpenJDK 64-Bit Server VM (build 11.0.5+10-post-Ubuntu-0ubuntu1.1, mixed mode, sharing)

Running javac --version by terminal I get the following output:

javac 11.0.5

Going to the Settings of the Java Compiler ( as suggested here ) I see this:

I tried editing the "Target bytecode version" to 1.8 but I get the following errors:

Error:(1, 26) java: package javafx.application does not exist
Error:(2, 20) java: package javafx.stage does not exist
Error:(4, 27) java: cannot find symbol
  symbol: class Application
Error:(12, 23) java: cannot find symbol
  symbol:   class Stage
  location: class Main
Error:(7, 9) java: cannot find symbol
  symbol:   method launch(java.lang.String[])
  location: class Main
Error:(11, 5) java: method does not override or implement a method from a supertype

Changing it to version 1.11 I get this error instead:

Error:java: Source option 5 is no longer supported. Use 6 or later.

What do you think is the problem? How may I solve it?

Solution 1:

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.

Solution 2:

Took me a while to aggregate an actual solution, but here's how to get rid of this compile error.

1. Open IntelliJ preferences.

2. Search for "compiler" (or something like "compi").

3. Scroll down to Maven -->java compiler. In the right panel will be a list of modules and their associated java compile version "target bytecode version."

4. Select a version >1.5. You may need to upgrade your jdk if one is not available.