I think it is a security issue of JAVA 8.
I uninstalled JAVA 8 and installed JAVA 7, with JAVA 7 Sweethome 3D works.

Hello,

since yesterday the launch of Sweethome 3D by java no longer works.
I have this error message:
java.lang.SecurityException: illegal URL redirect
I have already uninstalled and reinstalled Java.
I did everything that was indicated in the FAQ, but nothing works.

My computer is a bit old, I ...