Http error 500


I was working on a dashboard in Habpanel. When I tried refreshing my browser to see what the dasboard looked like I get the following:

I have tried restarting my OH2 server but still the same error.
The openhab log shows the following:

What do do now?

So… to reply to myself… I found this post:

regarding the same problem. And doing an upgrade of the installation seems to have fixed my issue.