1) make a backup of database and website
2) run SQL upgrade scripts
Copy and execute in Query Analyzer under survey database:
1) Run v4.164(?.x version that you have installed) to v5.0 (find script in zip file called: "Documentation/MSSQLScripts/MSSQL.../Upgrade/old version upgrade scripts to v5.000.x/upgradeNET-v4.164.x-to-latest.txt)
2) Run v5.0 to v5 latest version (find script in zip file called "Documentation/MSSQLScripts/MSSQL.../Upgrade/UpgradeNET-v5.000.x-to-latest.txt)3) overwrite files on website except uploadedimages folder
4) copy connection string, smtp info and license keys from old web.config into new web.config - change password encryption in web.config to off if your passwords are not encrypted or you won't be able to login. <add key="DATABASE_PASSWORD_ENCRYPTION" value="no"/>
5) login and click your name in upper right corner then click "admin tools" from pop up menu.
6) make sure URL and customer ID is filled in as well as force SSL and other GDPR settings indicated by GDPR logo, under "security - xframes" select "from trusted URL", click "Save"
You should be good to go at this point and everything should be working as normal.