Validation of viewstate MAC failed - ASP.NET Error

---

  
Free Lessons for Chruch Pianists:
Free lessons, tips and downloads for church pianists

DVD Courses (Reharmonization, Play by Ear!, Arranging, Accompanying, Theory for Church Pianists, etc.):
Over 30 hours of DVD instruction for church pianists

 

---

Server Error in '/Login' Application.

Validation of viewstate MAC failed. If this application is hosted by a Web Farm or cluster, ensure that <machineKey> configuration specifies the same validationKey and validation algorithm. AutoGenerate cannot be used in a cluster.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.Web.HttpException: Validation of viewstate MAC failed. If this application is hosted by a Web Farm or cluster, ensure that <machineKey> configuration specifies the same validationKey and validation algorithm. AutoGenerate cannot be used in a cluster.

What I did to solve this.

I removed the action attribute in the <form> tag.

I changed

<form id="form1" action="DisplayName.aspx" runat="server">

into

<form id="form1" runat="server">

and placed

Response.Redirect("DisplayName.aspx");

in code behind file.