“Unable to import file” error when trying to open an old After Effects project

I'm going through the archives of my department - from before I joined the company. I am trying to open and review AE projects from around 2014-2017 in AE version 24.4. When trying to do so, I get the error "After Effects warning. Unable to import file "{file path and name}" as project (bad format or not readable).” I've also tried importing the old projects into a newly created AE project with the same result.

Is there any hope for these old projects, or are they gone forever?