سوال: رفع خطا

با سلام
با C#‎ برنامه لاگین را نوشتم پس از اجرا هنگامی که دکمه ثبت نام را میزنم پیغام خطای زیر می آید لطفا راهنمایی کنید
Server Error in '/' Application.

Default Membership Provider must be specified.

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.Configuration.Provider.ProviderException: Default Membership Provider must be specified.

Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace:

[ProviderException: Default Membership Provider must be specified.]
System.Web.Security.Membership.InitializeDefaultPr ovider(Boolean initializeDefaultProvider, MembershipSection settings) +10171874
System.Web.Security.Membership.Initialize() +457
System.Web.Security.Membership.get_Provider() +10
System.Web.UI.WebControls.LoginUtil.GetProvider(St ring providerName) +41
System.Web.UI.WebControls.CreateUserWizard.get_Que stionAndAnswerRequired() +99
System.Web.UI.WebControls.CreateUserWizard.UpdateV alidators() +1378
System.Web.UI.WebControls.CreateUserWizard.CreateC hildControls() +36
System.Web.UI.Control.EnsureChildControls() +97
System.Web.UI.WebControls.Wizard.OnInit(EventArgs e) +111
System.Web.UI.Control.InitRecursive(Control namingContainer) +142
System.Web.UI.Control.InitRecursive(Control namingContainer) +318
System.Web.UI.Control.InitRecursive(Control namingContainer) +318
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +416

Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.8.4075.0
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