SyntaxError: Unexpected token '<'" when uploading media data

Online experiments
,
1

OS: macOS Tahoe 26.0.1

PsychoPy version: PsychoPy 2026.1.3

Standard Standalone Installation? Yes

URL of experiment: exp [PsychoPy] and exp [PsychoPy]

Do you want it to also run locally? No, running it on Pavlovia.

What are you trying to achieve?:
I am trying to run an online PsychoPy/Pavlovia experiment that includes movies and webcam recording/media data upload. The experiment was running before, but now it fails online during/after a movie when trying to upload media data.

What did you try to make it work?:
I synced the PsychoPy project to Pavlovia/GitLab again. I checked that the .psyexp and .js files were updated in GitLab. I also tried running the experiment again after pushing the updated files. The same issue still occurs.

What specifically went wrong when you tried that?:
When I run the experiment on Pavlovia, it starts, but after the first movie/media-recording routine it fails while uploading media data. I have 4 recordings of 8-11 minutes each, and 8 of around 1 minute each. First two recordings of 1 min each were uploaded but after that the next big one throws an error. The error message is:

Error

Unfortunately we encountered the following error:

  • when uploading media data for experiment: avisha/memory_eyetracking_test_v2

  • SyntaxError: Unexpected token ‘<’, "

Try to run the experiment again. If the error persists, contact the experiment designer.

Another time I just opened the dashboard and got this error "Error when authenticating the designer

>>> SyntaxError: Unexpected token ‘<’, "

If the error persists, contact Pavlovia’s administrator.

Full description:

{
  "error": {}
}

There were some authentication issues too initially, so I created a new experiment (v2 link above) but v2 also had similar unexpected token issues.

2

Hi. We’ve been having CPU load issues over the past few days (caused by malicious bots). Please could you let me know what time you got the error and I’ll see if it coincides with one of the spikes.

3

Hi,

I have been getting this error continuously for the past two days. First time it occurred around June 27 10:30 PM PST. The above experiments were created using 2026 psychopy version and they have this media upload issue. However, an older experiment with the same size of media upload is running. That was designed using 2024 version. Its here: exp [PsychoPy]

One additional detail that may be relevant: the newer experiments are not identical to the older one. The 2026 experiments include the beta Face API feature (which I mentioned in my original post), along with a few additional routines. However, I also tried disabling the Face API completely and still encountered the same media upload error.

That said, I don’t think these differences are directly related to the issue, because the experiment runs normally up to the point where it attempts to upload the media. The error only occurs during the media upload step.

4

Hi, I tried the 2024v experiment which also had the same size media uploads with 2026 version of psychopy and encountered the same error of unexpected token and media upload failed. But, before the outage, 2026 version was working and after outage it failed.