Sweet Home 3D JS Online

[Puybaret]

Maybe you upgraded the Java version. Check you use Java 11.

[TwistedLincoln]

I didn't update anything, and am running Java 11, so that wasn't it.

I "fixed" this issue, though still don't know how it happened to begin with.

After checking my Tomcat logs, there was an error referencing an invalid SSL certificate when accessing the JS applet. I use a self-signed one, but it has always worked fine before so this seemed odd.

I accessed the applet using the regular non-SSL link, and things worked fine again -- even when switching back to the SSL method. I didn't actually change anything. Odd.