# Running PsychoPy tasks on Pavlovia: coder-only task (403 error) and Builder task issues

**URL:** <https://discourse.psychopy.org/t/running-psychopy-tasks-on-pavlovia-coder-only-task-403-error-and-builder-task-issues/46462>\
**Category:** Online experiments\
**Tags:** pavlovia\
**Created:** [January 23, 2026, 5:59am UTC](https://discourse.psychopy.org/t/running-psychopy-tasks-on-pavlovia-coder-only-task-403-error-and-builder-task-issues/46462 "2026-01-23T05:59:43Z")\
**Posts on this page:** 1\
**Showing post:** 4

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**Author:** ![JensBoelte](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.psychopy.org/jensboelte/32/9060_2.png) [@JensBoelte](https://discourse.psychopy.org/u/JensBoelte)\
**Post date:** [January 23, 2026, 11:02am UTC](https://discourse.psychopy.org/t/running-psychopy-tasks-on-pavlovia-coder-only-task-403-error-and-builder-task-issues/46462/4 "2026-01-23T11:02:53Z")

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Hello @JKim

look here

> [@Wakefield's Daily Tips](https://discourse.psychopy.org/t/wakefields-daily-tips/43371/6):
>
> Use Auto → JS code components wherever possible Even if you aren’t planning to run your experiment online, using an Auto code component will help you spot syntax errors in your Python code. There are some cases where valid Python code comes up as a Syntax error on the JavaScript side but these are rare and, when you encounter then, you can switch to a Both code component and edit or delete the JavaScript side to highlight the fact that they contain code that won’t run online unedited. …

and here for debugging online experiments

> [@Debugging online - Thomas's demos](https://discourse.psychopy.org/t/debugging-online-thomass-demos/21327):
>
> Hi, @thomas_pronk Could you please make your demos active again? I want to show some of my students how to debug online. Many thanks, Artur

Best wishes Jens

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