I recently was contacted about an error message nearly identical to the one you posted. After some trial and error, I found out that the respondent had cookies blocked in their web browser. Allowing cookies resolved the issue in my case.

Same issue! We also use the SSO authenticator for many of our survey and we also occasionally get reports of these errors and have had difficulty figuring out what's causing them. I just had a user report the problem on a survey that has low current usage, so I was able to clear out all in progress responses before she tried again. She tried from a different browser on the same computer and received the same error. Afterwards, there was a single new in progress response with no info other than her IP Address, start and stop time, and 0% progress. She never made it to the SSO screen so something went wrong prior to that redirect.
I suspected a cookie issue, which is why I asked her to try from another browser. After reading brianj 's post, I did a little testing with the latest versions of Safari, Chrome, and Firefox on Mac OS X Catalina. I was able to replicate the error message, but only on Firefox and only if I first blocked ALL cookies and then switched the setting to blocking third-party only. I couldn't generate the error in either Safari or Chrome.
Has anyone else experienced this problem or done any troubleshooting that could help?

https://www.qualtrics.com/community/discussion/comment/21108#Comment_21108I am just having the same problem you are talking about.
As it was my first survey in Qualtrics I sent it to my colleagues for testing before sending it to customers. My colleagues received the error message as soon as they clicked on the survey link (which I sent them via Qualtrics Mail). So they couldn't even start the survey.

https://www.qualtrics.com/community/discussion/comment/34676#Comment_34676You may have tried this already, but I was able to resolve this issue by instructing a respondent to allow cookies in their web browser. Hope this help!

https://www.qualtrics.com/community/discussion/comment/34704#Comment_34704Thank you brianj .
Also, I just received an answer from technical support:
This error can happen if you delete the Distribution List before the respondents open the survey link.
It can also happen, if you delete a respondent or if the respondent opted-out of your contact list before they started the survey.
This might also be worth checking out if the cookies aren't the problem.