Sometimes when you have very large pages of data in the administration screens inside Spira you may receive an error due to exceeding the default number of allowed form elements posting back data. This article provides a fixed for the issue.
Most of the artifacts in Spira are "soft deleted", i.e. they are simply marked with a deleted flag, and can be recovered easily by a project administrator using the Project History Changes option to review the changes, filter by deletes and revert the change. However when a system administrator deletes a whole project, it physically deletes the project and cannot be undone.