Google Cloud IN_USE_ADDRESSES quota exceeded.
Solution 1:
I can't take full credit for this answer - I just remembered this one - but a deployment to Google's cloud leaves the old deployment in place (and thus using an IP and your hard-earned money) indefinitely.
Deployments can be triggered with --stop-previous-version
to prevent this behavior, and you can use list and stop to find and remove the old deployments so they no longer use resources.
Solution 2:
I don't even have an app deployed, just a Kubernetes cluster, so none of the suggestions helped for me. I kept deleting the cluster then recreating.
Found this page that lists the external IPs in use, which seems to be the root of the problem. Should work no matter what the reason is for your used-up IP addresses: https://console.cloud.google.com/networking/addresses/list
For my case of load balancers being the problem: I deleted all my clusters and still saw addresses in use. Then I found this page that lets me delete the load balancer IP mappings: https://console.cloud.google.com/net-services/loadbalancing/advanced/forwardingRules/list Recreated the clusters and services, and everything works fine now.
I don't know why deleting the cluster didn't free the addresses this one time. Maybe because I cancelled in the middle of one cluster's creation.
Solution 3:
I got the same error, but the reason was that my build was pointing to a wrong project(gcloud config list). I had configured cloud SQL in my code but it was in a different project then the app engine where I was trying to deploy. The error shown was exactly as mentioned in the above issue.