It’s been just over a year when I deployed the RuleManager with a ClickOnce certificate. Today it expired. Visual Studio 2005 would suggest to generate a new certificate file, however none of the existing users would be able to update the Application (because of different certificate keys).
The error you would get is:
System.NullReferenceException: Object reference not set to an instance of an object.
at System.Deployment.Application.ApplicationTrust.RequestTrust(SubscriptionState subState, Boolean isShellVisible, Boolean isUpdate, ActivationContext actCtx, TrustManagerContext tmc)
at System.Deployment.Application.DeploymentManager.DetermineTrustCore(Boolean blocking, TrustParams tp)
at System.Deployment.Application.DeploymentManager.DetermineTrust(TrustParams trustParams)
at System.Deployment.Application.ApplicationDeployment.CheckForDetailedUpdate()There is a workaround made by Cliff Stanford RenewCert, which allows you to regenerate an expired certification.
Thanks Cliff!