Does WebInspst 17.20 upgrade from 17.10 is required a db schema changes?
I cannot recall. If you are using SQL Express with WebInspect, it does not matter since the updating occurs when you open older scans.
If a schema update is required, e.g. you use a Standard or Enterprise Edition MSSQL Server for your scan storage, then you will be prompted by WebInspect. Before you opt to let it Upgrade Automatically, take a moment to Copy the suggested query to TXT as a fall-back, and also be ABSOLUTELY certain you have a recent back-up of that scans database. Reversing a failure will require Support intervention. Just jump into SQL Studio and perform a Back-up right then. If the Automatic Upgrade button then fails you, you can run that Query manually in SQL Studio.