Error when piloting an experiment (unable to convert to a number)

Description of the two problems:

When I want to run (pilot) my experiment, the first action is to press ‘space’ after reading the instruction to start the experiment. If I do this, this message occurs:

“Diese Seite bittet Sie zu bestätigen, dass Sie die Seite verlassen möchten – Daten, die Sie eingegeben haben, werden unter Umständen nicht gespeichert.”

In english this might be:
“This page asks you to confirm that you want to leave the page - data that you have entered may not be saved.”

When I click “stay on the page”, this error message occurs:

"Unfortunately we encountered the following error:
when converting an object to its numerical form
unable to convert
to a number.

Try to run the experiment again. If the error persists, contact the experiment designer."

I have absolutely no idea what causes these two events (I use Firefox).

Can anybody help?

Thanks a lot in advance!


could you be so kind and post either your *.psyexp in way that it can be run or share your project on Pavlovia (basically making it public and sharing the link to the porject)?

Best Jens