Piloting my online experiment gets stuck on "initializing..."

Description of the problem:
I’ve uploaded my experiment to Pavlovia and when I try to run a pilot it reads “initializing the experiment” and nothing happens.
Offline, the experiment works. It include images, videos and keyboard (space, and keys 1 to 5)
I’ve updated my psychopy version to the latest but the problem lasts…

I’m not very familiar with writing python/java codes, I’m only experienced with the builder…
Can someone please help a desperate rookie?


Do you have any code components? Do they include imports?

Have a look at my crib sheet and the quick start guide (see pinned post).

Best wishes,


Thank you for your quick response!
I don’t have any code components. I do have loops, relying on xlsx files (lists of the videos which are presented randomly). I thought maybe saving those loop files as csv would help, however offline, with csv instead of xlsx, the videos are not presented.
I had a look at your crib sheet, as I saw you recommended it to previous questions, unfortunately it was very hard for me to follow.
Do you maybe have other suggestions?

Do you have any variable components or code on your other components? People sometimes think they aren’t using Python code when in fact it’s in a text box or location where the auto translate doesn’t reach.

I don’t have a variable component, not test…
I have images, keyboard (‘space’ in order to end the routine and move to the next), videos presented randomly and keyboard (‘1’ to ‘5’ in order to place an answer asked on the video) with a loop. That’s it…
Do you think it might be the xlsx files defining the loop?

Please could you message me a pilot link and I’ll look for an error message in the browser console?

Excel files work in principle. They can have issues, but not usually at initialising.


Thank you so much for your kind help

The console error is:

Uncaught SyntaxError: Unexpected token ','

Looking at the line number (468), you have a blank value for size in practice_videos.