Weird error message when running study?

Online experiments
1

URL of experiment: Pavlovia

Description of the problem:
My study was running fine online before, but now gives this weird error message:

Screenshot 2020-05-08 at 12.52.14
Screenshot 2020-05-08 at 12.52.141436×766 140 KB

What is causing this and how do I fix it?

Thank you!