OS:
macOS on Apple Silicon. Original experiment was created/synced on Mac M2; I am currently using Mac M5.
PsychoPy version:
PsychoPy 2024.2.4 standalone and PsychoPy 2026.1.3 standalone.
URLs:
Exp 1, synced with PsychoPy 2024.2.4 on Mac M5:
Exp 2, originally created/synced with PsychoPy 2024 on Mac M2, not re-synced for months:
What I am trying to do:
I have a Pavlovia experiment with webcam recording during:
- 1-2 minute calibration routines before each movie
- four movie-watching routines, each about 8-11 minutes long
What goes wrong:
The short calibration webcam recordings upload successfully.
The long movie webcam recordings fail intermittently during media upload with:
Error
when uploading media data for experiment: [experiment name]
SyntaxError: Unexpected token ‘<’
Sometimes one or two movie recordings upload and it fails later. Last night Exp 1 completed successfully with all four movie recordings uploaded. This morning the same Exp 1 failed again. Exp 2 was running smoothly until yesterday but now also shows the same error.
What I tried:
I tested in Chrome Incognito.
Both experiments were working until the recent Pavlovia/server outage a few days ago. Since then, large media uploads have become flaky.
When I download either experiment and re-sync it as a new Pavlovia project using PsychoPy 2026.1.3, media upload fails every time.
With PsychoPy 2024.2.4, newly synced projects are intermittent: sometimes they work, but mostly they fail.
Key point:
This seems specific to large webcam media uploads from the 8-11 minute movie recordings. The shorter calibration webcam uploads work.
Questions:
- Is
SyntaxError: Unexpected token '<'during media upload usually caused by Pavlovia returning an HTML error page instead of JSON? - Are there known size, duration, timeout, or server-load limits for webcam media uploads?
- Could the recent Pavlovia outage have affected reliability for larger media uploads?
- Has anything changed recently in PsychoJS/Pavlovia media upload handling?
- Are there recommended Camera settings for long webcam recordings on Pavlovia?
I posted about this few days back and at that time I thought problem is specific to 2026 version sync, but now I think it’s not version specific. SyntaxError: Unexpected token '<'" when uploading media data
Thank you!
