What version of the terraform binary did you upgrade from? Based on the error, it appears that you were using something pre-0.13.x. Based on reading, you must upgrade to 0.13.x (using
terraform 0.13upgrade and following along with these instructions). Terraform only supports upgrades from one major feature upgrade at a time.
Once you’ve upgraded your state, it should take to 0.14.x without any forced upgrade process (see here for more details).