The error is caused by an enhancement to Webview in APM 10.0. When a user logs into Webview, a unique token is created and added to the service endpoint of each service class before the service is invoked in Webview. A new token is generated for every Webview session. If a user session times out, or Webview or EM connectivity is lost, a user is logged out of Webview. Once the connection is restored, usually by the EM or Webview service being restored or a user logging in again, and the same browser session is used, the error will occur because an invalid token is provided.