Upgrade 3.9 to 4.5 error : An unhandled exception occurred while processing the request.

1. I successfully updated SQL to 4.30 using upgradescripts

2. Then I download the new 4.50.3 project

3. Copy Settings.txt to App_Data of the 4.50.3 project

4.Settings.txt content is as follows：
DataProvider: sqlserver
DataConnectionString: Data Source=xxxxx;Initial Catalog=xxxx;User Id=xxxx;Password=xxxx;Integrated Security=False;Persist Security Info=False;TrustServerCertificate=True

Nop 4.50 use appsettings.json file for DB connection string.
Please try to add connection string there
Or run the project and configure database from installation page

Presentation->Nop.Web->App_Data->appsettings.json:

  "ConnectionStrings": {
    "ConnectionString": "Data Source=*****;Initial Catalog=*****;Integrated Security=True;Persist Security Info=False;Trust Server Certificate=True",
    "DataProvider": "sqlserver",
    "SQLCommandTimeout": null
  },

Also similar error here https://www.nopcommerce.com/en/boards/topic/94612/database-automatic-upgrade-issue-from-4404-to-4503