Pavlovia error: Failed to load resource: the server responded with a status of 404 ()

[canda]

Hello,

I have created an experiment using PsychoPy v2026.1.3, in Builder, with some code using Code Components. The experiment runs locally without any issues.

When I run it online through Pavlovia (the project is currently in Pilot mode), I get the following error: Failed to load resource: the server responded with a status of 404 () psychojs-2026.1.3.css:1

I have read previous posts about these issues and checked my Pavolvia project code. As shown in the screenshot, the HTML and JS files are present.

I have also tried deleting the project and creating a completely new one from a fresh, unrelated folder, but the same error occurs.

For context, I also have an earlier version of this experiment stored in a different folder and linked to a separate Pavlovia project. That version runs correctly both locally and online. The main difference between the working and non-working versions is that I added a Progress Component to the new experiment, but I am not sure whether this is related to the issue.

Does anyone have any suggestions about what might be causing this problem?

Many thanks for your help!

[wakecarter]

Is Use Version in Experiment Settings blank? (answer should be yes)

Do you have a lib folder? (answer should be no)

Since you don’t have any data yet, you could try setting the project to inactive and then active again. Does it show the correct version on the project page?

[canda]

Thanks! Setting the project to inactive and then back to active (pilot) solved the issue.

Use Version in Experiment Setting was not blank, it was set to latest. I have tried changing it to blank several times, but it reverted to latest as soon as I closed and reopened the Settings and it did not solve the problem.

[wakecarter]

Excellent! I think there was a bug with “latest” which got solved in 2026.1.3 by merging it with blank.