I got this error while trying to publish a test page. Restarting RapidWeaver fixed it. I had worked on this file all day and it was not having any issues.
Thanks for the heads-up!
Have you managed to re-create this issue? Had you perhaps just updated your stacks or themes while RW was running?
I have not been able to recreate this yet. I was not actively developing anything while building the site. I did not update anything either.
Strange, let me know if it happens again as there’s not much we can do this end without details