"java.lang.invoke.StringConcatFactory cannot be resolved." recurring error in VS Code

Question

I'm currently making a project and this error pops up on the first line of VS Code whenever I use lines such as this:

return "UserProfile{" +
                "userName='" + playerName + '\'' +
                ", numKalahGamesPlayed=" + kalahPlayed +
                ", numAyoGamesPlayed=" + ayoPlayed +
                ", numKalahGamesWon=" + kalahGamesWon +
                ", numAyoGamesWon=" + ayoGamesWon +
                '}';

This error always pops up and doesn't go away until I use something other than the '+' key in System.out.println messages.

This error just appears and doesn't affect the functionality of the code and doesn't stop me from doing "gradle build" but is annoying to look at.

My program is in Java and I've already refreshed/restarted VS Code and I've clean the Java lang workspace multiple times but nothing works. I know that StringBuilder works and I know how to use it but it's much easier to use System.out.println();

Can anyone help me fix this problem?

Answer 1

Set compiler compliance level to Java 1.8.