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Pavlovia error message "ERR_TOO_MANY_REDIRECTS"

Hi all,

I, along with all my participants, are getting this error message on google chrome and a variation of it in firefox when trying to access my online experiment (built in the Builder with PsychoPy 3.1.2).


Here’s my experiment link:

I saw that recently there was an issue stemming from updates to the pavlovia server and psychojs library (Online experiments - PsychoPy).

Could this be a similar issue?


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Yes. I have a same issue.


I am having the same issue.

I notice your experiment will work if the URL is:

That new URL form was posted in the following thread:

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Thanks Gabriel.

My experiments work fine with this URLs :slight_smile:

Thank you so much Gabriel.

If anyone can figure out why the original link is not working, though, I would still really appreciate it as I’ve already sent out the original link to a variety of participants and platforms.

Here’s the original link again:

Hi @jon and community,

I am experiencing the same issues as described above:

Previous experiments of this form do not work:

But this url form does work:

My question is whether this new url form will be what we should use for all experiments moving forward (including old experiments), or is this a temporary situation? I have several experiments live that I’m deciding whether to pause and modify, and am planning to release several more, and am wondering what you recommend here.

Thanks again for all your help and feedback, it is greatly appreciated.


Yes the for of url with

works for all previous studies and is the intended url to use going forwards. It means that, at some point, we can separate the running of experiments from the rest of the site very easily. I’m not sure why the other format is not currently working though - the aim for the foreseeable futuer was to allow either option and gradually phase out the format

Good morning,

As you might have noticed, we have just updated Pavlovia. In addition to changes to the web interface, we have also made substantial changes to the server and to the back-end. Regrettably, some of those changes caused the redirection issue you experienced.

This has now been sorted. You’ll notice that URLs of the type are now automatically redirected to As Jon mentioned earlier, if would be great if people used instead of from now on. But we will keep both of them working so your legacy experiments are safe.

Many apologies for the distraction!
Best wishes,


Thank you for the quick reply. The old URLs are now working as you mentioned and redirecting to the new format.

And thank you very much for your continued effort with Psychopy and Pavlovia.