I've been dealing with this issue on a couple of my Fedora 32 machines.
It appears that the upgrade of icedtea-web from icedtea-web-1.8.2-3.fc31.x86_64 to
icedtea-web-2.0.0-pre.0.3.alpha13.patched1.fc32.x86_64 breaks the alternatives link to javaws.x86_64.

I have to downgrade icedtea-web to be able to run JNLPs