Welcome to the forum @error
On your job’s Destination screen 2, does the Test connection button succeed? It’s a small test.
I assume this is a new setup, and it’s not getting far on the backup. Are any files showing up on S3?
You can watch About --> Show log --> Live --> Retry, but I’d prefer to get a log file if anything’s weird.
Could not find file gave directions for a similar recent case. “Could not find file” was a follow-on error.
While more info is needed to figure out how to fix that, avoidance might be to solve the earlier failure.