Error Message after approving participants/adding them to the allowlist

Hi there,

We are having issues with the automatic invitations regarding Day 2 of our study. They participants enter their completion code, we add them to the custom allowlist and approve the completion code, but for some reason the participants do not get sent the link for Day 2 of the study. Whilst approving/adding to allowlist an error message pops up saying: “Sorry, we were unable to retrieve information from this study. Please try again later.” The participants are approved though and their Prolific IDs show up on our allowlist. Does anyone have any idea what might be wrong?

Kind regards,

Nicholas Lynch

I didn’t get an error like you did but I did have a similar issue a couple weeks ago with my longitudinal study participants not seeing part 2 of my study. Here is what prolific said as a work around:

If the Prolific ID is present in your allowlist but not in your submissions page, please try sending the participant a direct URL to your study. This URL should be of the form:

You can find your unique study ID by opening the study from your workspace and checking the URL in your browser. For example, if your study ID was 5bbb73d73cdd2a00013fa505 then you would send the URL

As long as participants are eligible for your study, the direct URL should enable them to sign up successfully. Otherwise, any error messages they receive there should help them to understand what’s causing the problem.

Thank you so much for the fast response, we will try that and hope that it works.


I had the same issues and tried that second approach as well where, after adding the participants to the allowlist but them not receiving a code, I sent them a link to the survey with the Study ID. However, when they clicked on the link, the got the following message:

You are ineligible to take part in this study. We apologise for the inconvenience. Your account is in good standing.

I have reached out to Prolific and am still waiting to hear back from them about what to do.
I partly wanted to let you know that I too have trouble with this issue!


What worked for us is pausing the study and starting the second day again. What also works is trying to add the Prolific IDs multiple times to the allowlist, at some point the ID is at least added to the list, though you will not be able to see the participants ID in your submission section, only in the study details. The ID will then be added after the participant entered the completion code.

Other than that and contacting the participants I do not have any further idea, though you could try to duplicate your study - maybe that helps.