When trying to swap an Azure website from staging to production I got this error:
Switch-AzureWebsiteSlot : ExpectationFailed : Cannot swap site slots for site 'xxx' because the 'staging' slot did not respond to http ping.
I got this error in the preview portal, the old one and from the powershell command.
The staging slot is up&running before the swap but I saw that after the swap failure it takes time to access it. I understand from a quick search on Google that the staging slot is restarted before swapping to be "hot", but I imagine that the ping is done after the restart?
This is a known issue and Microsoft product team is troubleshooting this on high priority
Please follow this thread for updates https://social.msdn.microsoft.com/Forums/en-US/14a5afa7-f7df-4e4d-bac9-4d0334f1d6b0/cannot-swap-slots-anymore?forum=windowsazurewebsitespreview