Error: There was an unhandled exception on the current circuit, so this circuit will be terminated. For more details turn on detailed exceptions by setting 'DetailedErrors: true' in 'appSettings.Development.json' or set 'CircuitOptions.DetailedErrors'.

JavaScript
services.AddServerSideBlazor().AddCircuitOptions(options => {  options.DetailedErrors = true; });
services.AddServerSideBlazor().AddCircuitOptions(o =>
{
    if (_env.IsDevelopment()) //only add details when debugging
    {
        o.DetailedErrors = true;
    }
});
WebHost.CreateDefaultBuilder(args).UseSetting(WebHostDefaults.DetailedErrorsKey, "true")

Source

Also in JavaScript: