Blazor WASM different behaviour in production environment and local/dev

Question

When using XML validation in Blazor (with .NET 5), if an error is generated, the error message is reported as expected in a local development environment (debug or release modes) but incorrectly in a production environment (i.e. published to a static blob - no ASP.NET server)

In the code below, I'm intentionally generating an error to illustrate the problem.

    protected override async Task OnAfterRenderAsync(bool firstRender)
    {
        var xml = "I am not XML";

        // Create the XmlReader object from the string
        using (var reader = XmlReader.Create(new XmlTextReader(new StringReader(xml)), new XmlReaderSettings
        {
            ValidationFlags = XmlSchemaValidationFlags.ReportValidationWarnings
        }))
        {
            try
            {
                while (reader.Read()) ;
            }
            catch (XmlException exception)
            {
                Console.WriteLine (exception.Message);
            }
        }

The expected error message is:

Data at the root level is invalid. Line 1, position 1.

However, in a published/production environment this is:

Xml_MessageWithErrorPosition, Xml_InvalidRootData, 1, 1

I am guessing that these Xml_ references are internal Microsoft string references that are not available in the published environment and that Blazor doesn't include these to keep the download light, but I am wondering:

Why is there a different behaviour here? How can I reproduce the published environment behaviour locally? Is it possible to deploy the required modules required to get these error messages to be displayed. How can I identify what these are and ensure they are deployed?

Answer 1

<UseSystemResourceKeys>false</UseSystemResourceKeys> 

Issue explained at https://github.com/dotnet/runtime/issues/49308