Encountered an error on Citrix StoreFront 3.0 today regarding authentication.

All users received the well known error “Cannot complete your request” upon login.

Event Log on StoreFront-server showed errors with ID 10: “A CitrixAGBasic Login request has failed. Citrix.DeliveryServicesClients.Authentication.AG.AGAuthenticatorException, Citrix.DeliveryServicesClients.Authentication, Version=3.0.0.0, Culture=neutral, PublicKeyToken=null Authenticate encountered an exception. at Citrix.DeliveryServicesClients.Authentication.AG.AGAuthenticator.Authenticate(HttpRequestBase clientRequest, Boolean& passwordSupplied) at Citrix.Web.AuthControllers.Controllers.GatewayAuthController.Login()”

and ID 2: “Access is denied. Contact your system administrator. System.ServiceModel.EndpointNotFoundException, System.ServiceModel, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089 There was no endpoint listening at net.pipe://localhost/Citrix/Authentication/Win32 that could accept the message. This is often caused by an incorrect address or SOAP action. See InnerException, if present, for more details.”

Turns out the service  called “Citrix Default Domain Services” had actually stopped. Next time I will definitely check the running services before starting troubleshooting on IIS and Citrix Netscaler.