Error message - 404 file not found

Problem

OWA suddenly stops after updates or a reboot, and gives the following error message: 404 file not found.

Solution

1. Log in to the webserver and open IIS7.
2. Collapse everything until you can see all websites. The one called SBS Web Applications should be in stop modus (it shows a small stop sign).
3. Click right on Default Web Site and go to Edit Bindings.
4. Delete the SSL 443 reference. This website is not used for SBS but still has SSL assigned, this causes the error message.
5. Click right on SBS Web Applications and go to Edit Bindings.
6. Double click on the 443 reference (or make a new one for SSL 443) and assign the right certificate.
7. Click on OK until you're back on the website list.
8. Click right on SBS Web Applications and go to Manage Web Site → Start.
9. Test OWA, it should work now.