What is causing this GCP GAE [RESOURCE_EXHAUSTED] quota error?

Question

When deploying to GCP App Engine (Flexible) I'm getting a [RESOURCE_EXHAUSTED] error that I can't seem to make sense of.

The requested amount of instances has exceeded GCE's default quota.

Full error:

ERROR: (gcloud.app.deploy) Error Response: [8] Flex operation projects/project/regions/europe-west3/operations/8824354e-eaaf-45a6-9760-47167218e043 error [RESOURCE_EXHAUSTED]: An internal error occurred while processing task /app-engine-flex/insert_flex_deployment/flex_create_resources>2020-12-27T11:41:01.342Z18480.xj.2: The requested amount of instances has exceeded GCE's default quota. Please see https://cloud.google.com/compute/quotas for more information on GCE resources

Could this be related to my app.yaml configuration?

runtime: custom
env: flex
resources:
  cpu: 2
  memory_gb: 1.4
  disk_size_gb: 10
network:
  name: default
liveness_check:
  path: "/liveness_check"
  check_interval_sec: 30
  timeout_sec: 4
  failure_threshold: 2
  success_threshold: 2
  initial_delay_sec: 300
readiness_check:
  path: "/readiness_check"
  check_interval_sec: 5
  timeout_sec: 4
  failure_threshold: 2
  success_threshold: 2
  app_start_timeout_sec: 300
automatic_scaling:
  min_num_instances: 1
  max_num_instances: 15
  cool_down_period_sec: 180
  cpu_utilization:
    target_utilization: 0.5
  target_concurrent_requests: 100

If not, then what could it be related to?

Checking the quotas page shows that all quotas seem to be within limits.

Answer 1

As per the GCP doc the parameter 'max_num_instances', The maximum number of instances in your project should be 8 by default where I can see you are using 15. I would like to suggest you to increase the quota limit for your project will solve the issue.