Has been compiled by a more recent version of the Java Runtime (class file version 57.0)

Demystifying the error

Stumbling upon the UnsupportedClassVersionError? It signifies a tango of JDK versions during compilation and Java Runtime version during execution. Each Java release has a unique class version number, and older runtimes throw tantrums when asked to read classes compiled with newer JDKs.

Pinpointing the Environment Setup

Are your Java versions playing hide and seek? Use java -version to unveil them and ensure your PATH, JAVA_HOME, and JRE_HOME environment variables have got the correct Java version directories right. If the demon error lurks, follow:

1. Peep into SDK: In IntelliJ, knock on Project Structure → Project settings. Set the Project SDK to a hospitable version looking after class file version 57.0.
2. Set the PATH: Move the updated JDK location to the PATH's catwalk.
3. It's a match: In Windows, use an environment variable editor to avoid syntax blunders.

Navigating Project Configuration

Keeping with the times

Make Gradle sync with the Project SDK. If Maven is your BFF, reassure the compiler plugin to follow the correct version.

Cleaning spree

Problem-eyed developers reach here. Purge IntelliJ's cached files in a jiffy (File → Invalidate Caches / Restart). Go a step further, slash the IDE's build directory, and make a fresh start.

Troubleshooting the Versioning Conflict

Marching the JDK and JRE together

Dealing with expansive versions of Java Development Kit or JRE? Tame them by keeping only the ones you need around, and avoid messy clashes.

Choosing the Language Level wisely

In IntelliJ, set Project language level to "SDK default" for conflict-free development.

Wise Compilation Approach

Got to deliver on multiple open JDK versions? Compile with the -release flag targeting one specific Java release to ensure peace on all fronts.