That is an odd one, Have you made any big changes recently like going from an older version of n8n to a newer one? You have also not completed the template, Can you share how you are running n8n? Are you also using one of our main releases or a fork?
I used version 1.6.0 before, and ran for a while, but then suddenly this error appeared, whenever I reboot, it will return to normal for a moment, but soon will fail again, so I backup the workflow, delete all the workflow, or failed. So I tried to improve the version to 1.17.0, but it was still unsuccessful. It seems that the search workflow page always reports this error.