Pavlovia takes only first letter of CSV/XLSX condition file's cell - unknown resource issue


URL of experiment: Sign in · GitLab

Description of the problem:
I am trying to run an online experiment based on video stimuli displayed in a loop. In the loop component of PsychoPy I defined my condition file, containing path to all of videos, stored in ‘allName’ variable. This variable is later used in video component inside of a loop.

Everything works fine, when I run the study using PsychoPy Runner, but I met an issue after uploading the study to Pavlovia. The problem regards setting ‘allName’ variable, as far as I am concerned. The component spreadsheet is reached correctly, but cells of this file are not being read properly. Instead of full content of the cell, variable ‘allName’ is set to the first letter of it, e.g cell “stimuli/01010301010102.mp4” is read as ‘s’. I tried both xlsx and csv file type, different paths and different names of mp4 files, but I always get the same error, presented in below screenshot:

I would be grateful for any tips on what could be wrong.
Thank you in advance for your help.
Kind Regards,

I think this might help and give you some ideas.
I think that it is reading the first letter of stimuli/01010301010102.mp4, I think that is because you are subsetting the second row of the wszystkie.csv file

Hope this helps

Dear jp-psycholojs, thank you very much for you response! I have deleted the loops in first three trial sessions and wrote the path exactly to the file. The last loop - actual experiment, seems to work quite ok, although one more problem occurred - while presenting the video, only audio works, video isn’t displayed (only the background colour is visible). I have checked similar topic (Problem with running video files in Pavlovia - #4 by jonathan.kominsky) where the solution was to encode .mp4 with h264 codec, so I tried this, but unfortunately it still doesn’t work.

Those are details of one of my video files:

I have deleted the experiment and uploaded it again, here is the new link: Karolina Ćwik / test7 · GitLab

Thank you very much in advance :slight_smile:


Did you resolve this?
I have suddenly started getting the same issue, but cannot see what I have done differently.


Hello John,

I managed to resolve video’s black screen issue. I compared my JS code to the working one, which I found on Gitlab, and I noticed the differences. The key thing was to remove lines like:;
for every movie component. Videos are displayed properly right now. If you want to check out my code, you can find it here:

Keep my fingers crossed!

Ah. Sorry - I meant the original problem. I’m getting exactly the same issue of Pavlovia complaining about an unknown resource, and it’s saying, for instance ‘d’, where the excel file has ‘da010_441.wav’ in the cell.


Hi John,
I am having the exact same issue! Have you found a solution since?

Hi Katy,

Yes, I have been meaning to post about this, but haven’t had time to characterise exactly what is going on.

It appears to be a bug (in my case at least). I was using the facility to use only certain rows from the excel file in a loop. In translation from Python to JS it appears that this is mistranslatated as only the certain characters from a cell - I asked for only row 1 and I got only 1 character. I have not experimented with this hypothesis, but it’s my best guess. Certainly getting rid of the row selection removed the problem. I worked around it by using different columns instead of different rows. This was still awkward, because all the columns have to have the same number of rows.


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Hi CullingJ,

I am having the same issue with an experiment. Could you maybe explain in more detail how you worked around it by using columns? That would help me a lot since I have not been able to do it.