I'm running into an issue after installing a CU in my SharePoint 2013 farm. Installed the CU restarted my AP server, stopped services: spadminv4, sptimerv4, sptracev4 spwriterv4 and w3svc. Ran the PSCONFIG.exe command: 

    PSCONFIG.EXE -cmd upgrade -inplace b2b -wait -force -cmd applicationcontent -install -cmd installfeatures -cmd installcheck -noinstallcheck 

And the upgrade fails. here's the error message in the logs: 

> Failed to upgrade SharePoint Products. An exception of type
> System.NullReferenceException was thrown.  Additional exception
> information: Object reference not set to an instance of an object.
> System.NullReferenceException: Object reference not set to an instance
> of an object.    at
> Microsoft.SharePoint.Upgrade.SPContentDatabaseIntegrity.CheckAppOrphans()
> at
> Microsoft.SharePoint.Upgrade.SPContentDatabaseIntegrity.Check(SPContentDatabaseIntegrityCheckOptions
> options)    at
> Microsoft.SharePoint.Upgrade.SPContentDatabaseSequence.ContentDatabaseDataIntegrityCheck()
> at Microsoft.SharePoint.Upgrade.SPContentDatabaseSequence.PreUpgrade()
> at Microsoft.SharePoint.Upgrade.SPUpgradeSession.Upgrade(Object o,
> Boolean bRecurse)    at
> Microsoft.SharePoint.Administration.SPPersistedUpgradableObject.Upgrade(Boolean
> recursively)    at
> Microsoft.SharePoint.Administration.SPDatabase.Upgrade(Boolean
> recursively)    at
> Microsoft.SharePoint.Administration.SPContentDatabase.<>c__DisplayClass2.<Upgrade>b__0()
> at Microsoft.SharePoint.SPSecurity.RunAsUser(SPUserToken userToken,
> Boolean bResetContext, WaitCallback code, Object param)    at
> Microsoft.SharePoint.Administration.SPContentDatabase.Upgrade(Boolean
> recursively)    at
> Microsoft.SharePoint.Upgrade.SPUpgradeSession.ReflexiveUpgrade(Object
> o, Boolean bRecurse)    at
> Microsoft.SharePoint.Upgrade.SPUpgradeSession.Upgrade(Object o,
> Boolean bRecurse)    at
> Microsoft.SharePoint.Administration.SPPersistedUpgradableObject.Upgrade(Boolean
> recursively)    at
> Microsoft.SharePoint.Upgrade.SPUpgradeSession.ReflexiveUpgrade(Object
> o, Boolean bRecurse)    at
> Microsoft.SharePoint.Upgrade.SPUpgradeSession.Upgrade(Object o,
> Boolean bRecurse)    at
> Microsoft.SharePoint.Administration.SPPersistedUpgradableObject.Upgrade(Boolean
> recursively)    at
> Microsoft.SharePoint.Upgrade.SPUpgradeSession.ReflexiveUpgrade(Object
> o, Boolean bRecurse)    at
> Microsoft.SharePoint.Upgrade.SPUpgradeSession.Upgrade(Object o,
> Boolean bRecurse)    at
> Microsoft.SharePoint.Administration.SPPersistedUpgradableObject.Upgrade(Boolean
> recursively)    at
> Microsoft.SharePoint.Upgrade.SPUpgradeSession.ReflexiveUpgrade(Object
> o, Boolean bRecurse)    at
> Microsoft.SharePoint.Upgrade.SPUpgradeSession.Upgrade(Object o,
> Boolean bRecurse)    at
> Microsoft.SharePoint.Administration.SPPersistedUpgradableObject.Upgrade(Boolean
> recursively)    at
> Microsoft.SharePoint.Upgrade.SPUpgradeSession.ReflexiveUpgrade(Object
> o, Boolean bRecurse)    at
> Microsoft.SharePoint.Upgrade.SPUpgradeSession.Upgrade(Object o,
> Boolean bRecurse)    at
> Microsoft.SharePoint.PostSetupConfiguration.UpgradeTask.Run()    at
> Microsoft.SharePoint.PostSetupConfiguration.TaskThread.ExecuteTask()


Any ideas as to why it's failing?