As the title says, I get this error while building my code but I'm not using the calendar.

I'm using this version of java and I'm using SDK 17.0 in IntelliJ, is there any reason this might be? every single one of my files is corrupt now, so no reason to post all of my code here.

CodePudding user response：

The issue was found. It was caused by a misalignment of the language level:

After aligning both to 17, it worked again.