I installed Java 16 and set it in the etc\netbeans.conf file
However, upon startup, all projects reported an error. NetBeans automatically set the Java Platform to JDK 16 for them, but the Source / Binary Format was still JDK 15.
So it was enough to change it to JDK 16, except for one project that still can't be run and I didn't figure out why.
To run this project I need to close NetBeans and run it again in Java 15.
Creating a new project in Java 16 would probably solve the problem, but why should I do it when there was no problem with all the other projects.