If you are receiving this error when trying to delete one of your google cloud projects- then this blog can help you.

Error

The project has a lien against it.

A liens is a lock you can put on an account to prevent accidental deletion.

You can validate the liens by typing

gcloud alpha resource-manager liens list

to delete the Liens type

gcloud alpha resource-manager liens delete [LIEN_NAME]

You can now delete the project