Error in Razor\Views...*.g.cshtml.cs page

Sometimes, particularly after upgrading from one .net core verison to another I see errors in g.cshtml.cs pages...

Severity	Code	Description	Project	File	Line	Suppression State
Error	CS0246	The type or namespace name 'VerifyCodeViewModel' could not be found (are you missing a using directive or an assembly reference?)	mysite	C:\apps\websites\mysite\obj\Debug\netcoreapp2.1\Razor\Views\Account\VerifyCode.g.cshtml.cs	23	Active

I can never remember what to do.

The trick is to go and look at the cshtml file (the razor view itself) that the .cs file is compiled from.

There will be an error and it will be evident in the cshtml file itself.

For some of them the error was that I had to add another @using statement to the _ViewImports.cshtml file. But it could be anything.