Adobe sesx mutisession file format unspported

I have been working on a project for some time, using an external hard drive to manage space on my Mac. I stepped out and returned when there was a power outage. Upon reopening the application, I encountered the error message, "Warnings or errors were encountered when opening the following file." The detailed tab below indicated "file format not supported."

Since then, I have attempted to open the backup files, but they all result in the same error.