jsPsych version (8.2.1) Project link: Pavlovia I have run an experiment using jsPsych hosted on Pavlovia recruiting via Prolific. Almost all of the data was collected and stored fine. However, 5 data sets for participants that completed the study (had the correct completion code for Prolific) just did not save and no credits were spent for these 5. I have now spent additional funds to replace them, but I am wondering why this might have happened. Could it possibly be something to do with the fact that I only assigned enough credits to complete data collection, but a total of 8 credits have been ‘reserved’. Could it be that Pavlovia stopped storing the data once it ran out of ‘assigned’ credits because some of them had been ‘reserved’? If not this, can you think of any other reason why a handful of data files did not save correctly even though the rest of them worked just fine? As I said, I have already paid additional participants to replace these lost data, but it would be good to know where the problem came from so that I can avoid it in the future.

Have you tried downloading the data from the project page? There have been some recent issues related to the connection between the run server and the gitlab server. [image] Data not being saved on gitlab BUT can be downloaded from pavlovia page Online experiments URL of experiment: Description of the problem: We ran 5 subjects through Prolific in the above task just to pilot and make sure everything is working. Everything seemed to go well, except that when I updated the git repository on my computer, there were 7 data files, and 1 participant seemed to be missing. When I check the Pavlovia dashboard it says 5 completed and 3 aborted, and when I download the data from the dashboard, indeed the zip file contains 8 data files. Why then are there only 7 … [image] Wakefield's Daily Tips Blog Download your data before switching your experiment to inactive When running an experiment on Pavlovia, the files exist on two separate servers. gitlab.pavlovia.org This is where files get uploaded when you sync from Builder. run.pavlovia.org A copy is created here when you activate a study (change to Piloting or Running). [image] Participant data is initially stored on the run server and then transferred to the GitLab server. If you download data from the project page you are download…

Yes, I downloaded the data. As I said, 5 credits were not used and 5 data files were not saved. Whatever happened, the credits were not spent either. Nonetheless, all participants successfully completed the experiment and provided the correct code having been automatically redirected back to Prolific.

If the credits weren’t spent, then was the completion code displayed on screen? [image] Wakefield's Daily Tips Blog Exit cleanly Locally you might want your participant to end on a thank you screen rather than being sent back to the PsychoPy Builder. Unfortunately, this desire has encouraged a bad habit of leaving the final message on screen and then pressing the escape button to exit. While data is saved locally after escape has been pressed, until recently microphone recordings were not. My recommendation would be to have the final screen end on a key press that you have not told the participant, e.g. ‘q’. … [image] Wakefield's Daily Tips Blog Daisy Chaining Daisy chaining means going from one web application to another in a single participant session. It normally requires passing the values of one or more variables from one app. to the next so that the data can be matched. There are two aspects to consider. The first is sending values TO Pavlovia. I highly recommend that you send a value for participant (without changing the spelling or capitalisation) since this value will start the data file and log file names. A column for sessi…

No, the completion code was in the return URL. It seemed to work fine for almost everybody… but I’m guessing it was the final 5 participants who took part who’s data did not save.

Hi, I’m also having an issue accessing my experiment data. I tested the study with one pilot participant through Prolific, as well as with myself, and in both cases no data were saved in the Pavlovia file. The study first runs on Pavlovia and then continues on LimeSurvey. I was able to retrieve the LimeSurvey data without any problem, which suggests that the participant completed the full study. However, no Pavlovia data file was generated for this participant. What is confusing is that the experiment works perfectly in pilot mode. When I test it locally, the data are saved correctly and I can download the files. The issue only appears when running the study online. When I tested the online version using the browser DevTools, I received several error messages, including a “500 Internal Server Error.” I am attaching a screenshot of the console so you can see exactly what happened. Would you be able to take a look at the error messages and let me know what might be causing the data-saving failure, and what I should adjust to prevent this from happening again? Thank you very much for your help. [Screenshot 2026-06-16 120036]

It’s really hard to know what has gone wrong in jsPsych scripts because of people writing their own code (and I’m afraid I don’t have time to inspect the code for individual studies). One common issue that we’ve seen when people write their own code, in any framework, is that they forget to await the call that pushes the data to the server. It’s really important to include an await call or your redirect will occur too quickly for the data to have saved. In @alexisb case I see you’ve got something in the manually asking the participants to look out for warning signs from the browser but I’m not sure these warning signs always occur. So I think the first port of call is to revisit your data saving code. Hope you find something :crossed_fingers:

'Some' data not saving for completed sessions recruited via Pavlovia

Online experiments jsPsych

wakecarter June 11, 2026, 8:22am 2

Have you tried downloading the data from the project page? There have been some recent issues related to the connection between the run server and the gitlab server.

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'Some' data not saving for completed sessions recruited via Pavlovia

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