New to Telerik Reporting? Download free 30-day trial

Anti-Forgery Token Issue Occurs in ASP.NET Core 2.1+ Applications


Product Progress® Telerik® Reporting
Project Type ASP.NET Core, ASP.NET Core MVC
Viewer Type HTML5 Report Viewer


When adding any of the following lines of code in the Startup.cs file, the report won't load and an error will be thrown.

Error Messages

The following error message occurs:

services.AddMvc(options =>
    options.Filters.Add(new Microsoft.AspNetCore.Mvc.AutoValidateAntiforgeryTokenAttribute()));

Alternatively, a similar error message is thrown:

services.AddControllersWithViews(options =>
    options.Filters.Add(new Microsoft.AspNetCore.Mvc.AutoValidateAntiforgeryTokenAttribute()));

Steps to Reproduce

  1. Implement the anti-forgery token. For example, in ASP.NET Core MVC application, create a new GetAntiXsrfRequestToken() function on the viewer page to get the request token:

    @inject Microsoft.AspNetCore.Antiforgery.IAntiforgery Xsrf
        public string GetAntiXsrfRequestToken()
            return Xsrf.GetAndStoreTokens(Context).RequestToken;
  2. Add the function to each request header:

    <script type="text/javascript">
            $.ajaxPrefilter(function (options, originalOptions, jqXHR) {
                jqXHR.setRequestHeader("__RequestVerificationToken", '@GetAntiXsrfRequestToken()');

    As a result, the "Error registering the viewer with the service." error message occurs. Also, in the browser console on Register Client request returns 400 Bad Request with the following error:

Failed to load resource: the server responded with a status of 400 (Bad Request)
Uncaught (in promise) Invalid clientID


The AutoValidateAntiforgeryToken is recommended by Microsoft for non-API scenarios. When using this approach, that requires manually adding anti-forgery attributes. If you forget the attribute, no error will occur and the Controller/Action will not be protected. For that reason, the automatic approach is generally less error-prone and easier to maintain, especially if there are large number of Controllers and Actions that need this protection. You can use the AutoValidateAntiforgeryToken with the ReportsController provided that you do one of the following things:

The following configuration or its equivalent have to be replaced with the configuration that follows:

services.AddMvc(options => { options.Filters.Add(new AutoValidateAntiforgeryTokenAttribute()); });

The following configuration has to replace the previous one:

 services.AddAntiforgery(options => options.HeaderName = "__RequestVerificationToken");

See Also

In this article