"Cannot read property "lose context" of null"

Online experiments
1

URL of experiment: https://pavlovia.org/run/cmfo/free-gen-task/html/

Description of the problem: My participant was not able to run the task because these errors started to occur. The task was working normally for most people but this participant got the following errors:

“Cannot read property “lose context” of null”
“Cannot read property “style” of null”

What should I do to prevent it from happening again?

1 Like
2

Are you updating something every frame?

3

Yes, but so are other tasks. I think there is a problem with Pavlovia as everything was working well until last week. Most tasks give some error or stop running. What is going on with the site?

4

Hi @cat500, the same happened to me, only once to one participant. Did you figure out what it was? Thank you!

5

Same thing happened to one of my participants as well! This person said they got about an hour through before this. The screen went gray, they emailed me, and I told them to press ‘esc’ (not “x” out, to save partial data) and that is when the “lose context” error came up.
https://run.pavlovia.org/juliaschorn/pdm21/html

6

Lose context is indicative of a memory loss, which I think happens most often when the screen is being updated every frame instead of only when it changes.

7

Got it, that makes sense. Right now I have a break routine that should come after a certain number of trials so in Begin Routine I have: trialCount = (trialCount + 1);

And at each frame I have:
if ((((trialCount === 160) || (trialCount === 320)) || (trialCount === 480))) { continueRoutine = true; } else { continueRoutine = false; }

Is there a way to change this so that the experiment doesn’t need to be updated every frame?

8

That’s not the type of Each Frame code that might cause a memory error since it isn’t changing the display.

Do you have any components set to update every frame?

9

I don’t think I do, but it could be my stimulus- it is a movie file (.mp4) that is only 3s long and silent. It was meant to be a gif but that only worked in PsychoPy, not Pavlovia. The trial ends when the participant presses a key.

It is set every repeat (not every frame) however I did check ‘loop playback’- could that be it? Would the only solution be to not loop it?