Slider/components disappear in online experiment

While running my PsychoPy experiment on Pavlova, the webpage broke several times. In some instances, the webpage became completely blank, while in others, components like polygons and sliders vanished, leaving only the text elements visible on the screen. The log file reported errors with the message “autoDraw = null.”

For the slider question, the slider component disappeared, but the associated text remained on the screen.


Similarly, for another question involving a polygon (the “FILL” button), the programme failed to display the polygon and the colour of the polygon, leaving only the text element visible.


Hi Bihui,

Sorry you are experiencing this - we might need a bit more info to help here.

  1. What version of PsychoPy are you using?
  2. do you have a minimal demo of the issue? (e.g. a .psyexp file that contains only the routine where the issue occurs - e.g. the component disappears).

With that extra detail it should help us to replicate the issue so we can provide more help.


Hi Becca,

(1) I am using PsychoPy v2024.1.5.
(2) I’ve uploaded a minimal demo. I have two conditions (depends on whether the session is 0 or 1). The issue occurs in the routines “fill_trail” and “click_trail.” The slider question is in the routine “Prosocality.” I also included a log file when the webpage broke (it wrote autoDraw = null for many elements).

PsychoPy (786.5 KB)

Many Thanks!


Thanks Bihui,

Just to check - how is it that you produce the issue? do you press the esc key at a specific point? I am running a version of your task here in chrome and cannot replicate the problem - so wondering if a difference in browser or the way I am interacting with it?


The webpage only broke occasionally. I collected 50 participants in the lab (I use Chrome too), and it broke 3 times. So I actually don’t know when it will break. I just know that when it broke, the webpage turned completely blank. When I click “esc”, some elements show up on the screen (e.g., text) but not others (e.g., polygon, slider). Or when the webpage broke, some elements disappeared, and participants were not able to interact with the program anymore.