There's an important new blog post on our PWS blog about migrating from cflinuxfs2 to cflinuxfs3. If you are affected by this change, this is highly recommended reading for you. https://blog.run.pivotal.io/action-required-pws-default-stack-change/
If anyone needs instructions on how to migrate stacks, please see this KB -> https://community.pivotal.io/s/article/how-to-migrate-from-one-cloud-foundry-stack-to-another-stack