Getting error "WEB_HOOK channel unavailable" while watching Google calendar push notifications

Question

Currently I started getting:

{
  "code" : 400,
  "errors" : [ {
    "domain" : "push",
    "message" : "WEB_HOOK channel unavailable for: {address=https://...}",
    "reason" : "channelUnknown"
  } ],
  "message" : "WEB_HOOK channel unavailable for: {address=https://...}"
}

When I try to start watching Google Push Notifications. I have my domain verified and the url is available for Post Requests in the Internet. Notifications are just not coming to it. What might be wrong here?

Answer 1

It's an issue on Google's end. They are working on addressing it

https://issuetracker.google.com/issues/110373170#comment20

Credit: @dvelopp

Update: There was an issue with the Calendar API that was resolved

https://issuetracker.google.com/issues/110373170#comment26