IssueTracker

Currently, the only workaround available is to avoid creating the first few cloud SQL instances in the same network at once. After the first is created, the following ones can be created in parallel without any issue.

Suffering from this issue as well. I posted a question and workaround in Stack Overflow: https://stackoverflow.com/questions/55990713/how-to-fix-an-unknown-error-occurred-when-creating-multiple-google-cloud-sql-i/55991852#55991852.

We are experiencing the same problem when creating a postgres sql instance via Terraform.

I'm using UI to create a single MySQL, and seeing the same error now
Failed to create or a fatal error occurred during maintenance
An unknown error occurred

same for postgres with bot UI and terraform

I'm still seeing this issue as of April 2025. I just previously built up a cloud sql instance using Terraform then did a Terraform destroy. Now I'm trying to build a new instance and it's giving me this error:

│ Error: Error waiting for Create Service Networking Connection: Error code 9, message: Cannot modify allocated ranges in CreateConnection. Please use UpdateConnection. Existing allocated IP ranges: [private-ip-address].
│
│   with google_service_networking_connection.private_vpc_connection,
│   on main.tf line 55, in resource "google_service_networking_connection" "private_vpc_connection":
│   55: resource "google_service_networking_connection" "private_vpc_connection" {

Workarounds trying different naming, and update connection doesn't seem to work. Seems like the only workaround is creating a new VPC to do deployments.