The anti-forgery token could not be decrypted

Question

I have a form:

@using (Html.BeginForm(new { ReturnUrl = ViewBag.ReturnUrl })) {
@Html.AntiForgeryToken()
@Html.ValidationSummary()...

and a

Answer 1

My fix for this was to get the cookie and token values like this:

AntiForgery.GetTokens(null, out var cookieToken, out var formToken);

Answer 2

Just generate <machineKey .../> tag from a link for your framework version and insert into <system.web><system.web/> in Web.config if it does not exist.

Hope this helps.

Answer 3

I get this error when the page is old ('stale'). A refresh of the token via a page reload resolves my problem. There seems to be some timeout period.

Answer 4

you are calling more than one the @Html.AntiForgeryToken() in your view

Answer 5

I got this error on .NET Core 2.1. I fixed it by adding the Data Protection service in Startup:

public void ConfigureServices(IServiceCollection services)
{
    services.AddDataProtection();
    ....
}