What does this Blazor error message mean?

Question

If I told you that "You require sunglasses or an umbrella but not both." you would have no idea if it is raining or not. When running my Blazor web application I get

EditForm requires a Model parameter, or an EditContext parameter, but not both

My code has:

<EditForm Model="@order" OnSubmit="OnSubmit">

so as far as I know I am only using a Model parameter. I think use of the word 'Or' in error messages should be banned. My guess is that something has auto generated EditContext. Has anybody got any idea where to look?

Answer 1

Did you create an instance for the variable @order? You will get this error message if you defined @order but leave it null.

If that's the case, it relates to the admittedly awkward error message because "EditForm requires a Model parameter, or an EditContext parameter", but you provided neither.

See: ASP.NET Core Blazor forms and validation : Troubleshoot

When assigning a Model to the form, confirm that the model type is instantiated