GCP - can't attach disk to an existing instance - google-cloud-platform

Question

I'm trying to attach a new disk to an existing instance.
I'm able to create the disk, however, when I try to attach it, it fails with the following error:
The resource 'xyz-compute#developer.gserviceaccount.com' of type 'serviceAccount' was not found.
What is preventing me here, and how can I add a disk?

Answer 1

The information requested by John Hanley would be very helpful to narrow down the issue and provide an accurate response to your question, however, that error message is typically shown when the Compute Engine default Service Account was deleted, if that is the case you have 3 possible options:
a) If the Service Account was deleted less than 30 days ago, it might be still possible to recover it using the command:
gcloud beta iam service-accounts undelete ACCOUNT_ID
The output of that command should look like this:
restoredAccount:
email: sa-name#project-id.iam.gserviceaccount.com
etag: BwWWE7zpApg=
name: projects/project-id/serviceAccounts/sa-name#project-id.iam.gserviceaccount.com
oauth2ClientId: '123456789012345678901'
projectId: project-id
uniqueId: 'account-id'
You can follow the steps here, in order to recover it.
b) If it has been more than 30 days and undeleting is not possible, you will have to create a new Service Account and set it as the default Compute Engine Service Account. The steps for this would be:
Create a new Service Account with the name of your choice
You can do it through Cloud console by navigating to IAM -> Service Accounts page and clicking on '+ Create Service Account'. Or, if you prefer using the gcloud command, you can create a new account by using the command:
gcloud iam service-accounts create <NEW-SA-ACCT-NAME> --display-name="Compute Engine default service account"
Get the email id associated with this service account either via Cloud Console Service Accounts page, or using the gcloud command:
gcloud iam service-accounts list
Once you have done the above steps, you can set this new Service Account as the Compute Engine default Service Account using the alpha command:
gcloud alpha compute --project=peya-data-ops-pro project-info set-default-service-account --service-account=<NEW-SA-ACCT-NAME-EMAIL>
Note: This command is currently in ALPHA and may change without notice. If this command fails with API permission errors despite specifying the right project, you may be trying to access an API with an invitation-only early access allowlist, as described here.
c) As a last option and as long as you don't have any other resources running in Compute Engine or you don't mind losing those resources, you can disable the Compute Engine Service following the steps here and then re-enable it following this guide, that will recreate the default SA and you will be able to complete the required process.