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Blank page when uploading experiment online

OS : Windows10
PsychoPy version : 3.01

Hi there,

I am trying to upload the experiment to Pavlovia. I can successfully upload everything from the PsychoPy GUI, and the html folder is there. However, when I try to launch it online, the web page is empty. I tried to use F12 and see if there is any error info, and Chrome shows the following:

When I put the mouse on the blue link, they all seems to indicate I am missing something in the folder ‘html/lib/’, which I dont have.

Then I tried Microsoft Edge as well, but the information is different:

One thing might be related: in the ‘html/resources/stimuli/’ folder, I found only 1 out of the 25 images is in the folder (all the others are not). I am not sure whether that is something concerning or might cause the issue?

As a side note, I didn’t use any code variables in the experiment. The name of the file and the project is also the same. I also built the whole thing in 3.01 today. So I am really not sure what is the problem. Here is the link to my experiment in case I was not clear:exp.

Thank you for your help in advance!!

Exactly the same for me!
A blank web page and I’ve test this again with a totally new project with just one screen.
Help please…

Hi both, would you please provide a link to your experiments? That would be helpful for debugging :slight_smile:

Of course, sorry for this mistake…
Like I said, I’ve just created a very small try which is there:

Before that, I had another problem with the csv format while saving the results… If you remember (Online experiment saved data was format misplacement)… Because I can’t save without errors, I’be tried to make another experiment with pictures instead of texts… Maybe with the new version, it will work. Anyway, the experiments with pictures don’t start either.

Sure! Here is the link to the experiment! experiment_link

I also put the link to the actual code in gitlab on the original post as well, in case it is helpful.
Also, I have to apologize in advance if you meet any permission issue. Do I need to make it public so you can view it?

By the way, as a concern, I did use participant number as a variable to access the corresponding csv file, as well as using other variables for images’s path location and images’ position on the screen. I am only wondering whether using participant number (which is stored as a Python dictionary if I remembered corrected), or any other variables (with which I concat some variables into string), will cause problem in the JS code. This is mentioned here because I also realized that none of the csv file is in the html folder.


Thanks for your patience. I believe the 404 error occurs because the the PsychoJS engine (currently 3.0.0) is in the process of being updated to the most recent release of PsychoPy (3.0.1). I believe this will be actioned tomorrow (Monday), but will check with @jon and the server team tomorrow and get back to you asap tomorrow.

The 404 error for the contindiff experiment is now fixed on the server. Sorry about that.

For the resources/stimuli, yes, at the moment PsychoPy isn’t correctly detecting stimulus locations when the filename is a variable (as in your case). If you could manually copy them into the html/resources/stimuli folder.

See how you get on once those are copied over

Hi David and Jon,

Thanks for your help! I can open the psychopy on line now!! I also moved all the images in the stimuli into the html/resources/stimuli folder.

However, I am having a new problem online. After I entered the subject number, this error showed up:

I have tried to move all subjects’ csv files into the html/resources/sub_file (locally, all my subject files are also in the sub_file folder), in case it is caused by PsychoPy not being able to detect each subject’s csv file (I guees it’s similar to the stimuli location, though not sure). but it didn’t help with this error. Any suggestions?

Thank you both so so much for your help again!

Quick Update: I don’t think the variables names are causing this problem. I just tried to build another experiment with no loop or variable, but it has the same problem.

That error was ours but it’s fixed now on the server. I think all you need to do is fully refresh the experiment in the browser (probably shift-R will refresh the javascript a well as the html code)

hi Jon,

Thanks for the reply! This error has disappeared now!! Sorry for this, but I have another question following up.

Initially, I have an error looks like this:

I believe it is caused by a polygon variable (fixation cross in my case). I am currently using a fixation picture instead of the polygon, so I can work around it. However, I am wondering whether there are problems with my polygon setting or the polygon is not in place yet? I did try other shapes or sizes, or changing between parentheses and bracket, but none of them seem to work.


Again, thank you so much for your help and time!! I am so glad everything is working now!

Sorry, but it doesn’t work for me.

when I try to activate the project Sign in · GitLab


I want to say to all the developers that all the problems that I had encountered are fixed! Thanks to all!
I needed to start a new experiment with the new version and to synchronize it on Pavlovia.
No more problem with the save of the CSV file!
Encore merci…

Because I use TextStim object, I encountered some options that are not generated by PsychoPy, per ex “alignHoriz : ‘left’”, which is very useful for the presentation of texts.
I don’t know where to put these kinds of observations…
Thanks again!