FAILED_PRECONDITION when trying to create a new Google API project

Question

I am getting an error when attempting to create a new project for Google API at https://code.google.com/apis/console

I was hoping the error was temporary, but I have

Answer 1

Looks like there's another possible cause, in addition to the one that @AndrewL provided in his solution.

Short answer:
I ran into the same error when I attempted to associate a new GCP project with our billing account via Terraform. Our billing account has a default limit of 5 projects (which we had already met), and this blocked the association of new accounts and generated the Error 400: Precondition check failed., failedPreconditionerror message. To fix, I had to remove/delete one of the already associated projects before I could add a new one.

Long answser:
Here is the error message I encountered in Terraform (sensitive data and IDs redacted):

An execution plan has been generated and is shown below.
Resource actions are indicated with the following symbols:
  ~ update in-place

Terraform will perform the following actions:

  ~ module..project
      billing_account: "" => ""


Plan: 0 to add, 1 to change, 0 to destroy.

Do you want to perform these actions?
  Terraform will perform the actions described above.
  Only 'yes' will be accepted to approve.

  Enter a value: yes

module..project: Modifying... (ID: )
  billing_account: "" => ""

Error: Error applying plan:

1 error(s) occurred:

* module..project: 1 error(s) occurred:

* google_project.project: Error setting billing account "" for project "projects/": googleapi: Error 400: Precondition check failed., failedPrecondition

Terraform does not automatically rollback in the face of errors.
Instead, your Terraform state file has been partially updated with
any resources that successfully completed. Please address the error
above and apply again to incrementally change your infrastructure.

My billing account was at its maximum of 5 projects. As a test, I removed one of the projects and then ran Terraform again. It then successfully added the new project to the billing account. To double check, I attempted to add yet another new project to the billing account (to push the amount to 6) and then received the same error message again.

Straight up deleting one of the associated projects also works.

It stands to reason that requesting a limit increase for your billing account's associated projects will also fix this issue.