I opened the Ruby console and then started the plugin, but there was no text in the console, so I think there's no problem there.
I don't think that there's a problem with my model. I tried it on different models and it wasn't working either.
Maybe there is a problem with LibFredo? I updated it last week and I haven't noticed any problem before. I tried reinstalling LibFredo and JPP, but it didn't fix anything.

Here is how it looks in SketchUp, no error message, just not working as intended:

Hi, first of all I really like this plugin and I have been using it for some time now. Somehow the face selection via surface stopped working for me. The plugin only selects by face if I set it to surface.