I upgraded a solution from 9.2.17 to 9.10.21 (with an intermediate step of 9.4.19) today. So, the upgrade path was 9.2.17--->9.4.19--->9.10.21. The issue I'm running into now is that the frontend of the site will no longer display. It is throwing a 404 error page now.
On 9.2.17, the homepage displayed correctly. On 9.4.19, the homepage displayed without formatting as if there was no CSS/stylesheet. Now on 9.10.21, the homepage displays the 404 error page.
On the backend event viewer, the only relevant message is the following:
Are there any other places I can look to determine why the website is throwing this generic error page? Is there an obvious step I could have missed when upgrading?
Clicking Go to the frontpage just leads to the same 404 page.