I encountered the following exception earlier today:
Unknown constant tag 32 in class file com/sun/org/apache/xerces/internal/impl/xs/XMLSchemaValidator
I didn’t do anything to cause it. It just appeared out of nowhere.
I’m proposing my own answer (see below) but if anyone wants to shed more light on it, please add your own answer.
Re-install your JVM
After first thinking it was something to do with dependencies, I quickly zeroed in on a corrupted file in my JDK installation. Re-installing immediately fixed it.