RAD PDF is blank after refreshing page when debugging ASP.NET Core / ASP.NET 5 / ASP.NET 6+ in Visual Studio

After refreshing the page, the RAD PDF interface may appear as a empty, blank white box instead of the normal interface. This can be caused by interference from Visual Studio's "hot reload" feature in its debugger.

Visual Studio's debugger attempts to inject HTML / JavaScript code to support this feature, but doing so interferes with RAD PDF's output. (This issue will not occur in production / IIS as it is specific to the Visual Studio debugger.)

In our sample projects on GitHub, you'll notice that our launchSettings.json files specify that "hotReloadEnabled" = false for our debugging profile, for example:

{
    "iisSettings": {
        "windowsAuthentication": false,
        "anonymousAuthentication": true,
        "iisExpress": {
            "applicationUrl": "http://localhost:60352",
            "sslPort": 0
        }
    },
    "profiles": {
        "IIS Express": {
            "commandName": "IISExpress",
            "launchBrowser": true,
            "environmentVariables": {
                "ASPNETCORE_ENVIRONMENT": "Development"
            },
            "hotReloadEnabled" : false
        },
        ...
    }
}

You can also disable CSS Hot Reload for all projects in Visual Studio's preferences (click Tools -> Options...) on the ASP.NET Core tab as shown below:

Also see:

https://stackoverflow.com/questions/69952420/how-to-disable-browser-link-in-asp-net-core-net-6-vs-2022