This error originated from recent new JDK 15 release which eliminated “Unpack200” bin from the package as C++ plugin hasn’t been available anymore under new “Netbeans Distribution” term.
If you encounter this, follow steps below to fix:
Step 1: Install JDK 11
Step 2: and reinstall JDK 15
Step 3: … Read more... “Fixing C/C++ plugin installation error on Apache Netbeans 12.x”