Many years ago, I was working on an application that would be delivered to the users on a DVD. (Not too long ago: software delivery by DVD was already exceptional rather than the rule.)
First DVDs were created and they didn't work.
I couldn't reproduce the issue with a fresh build.
I retrieve the application from the staging area (where we assembled the ISO): no problem.
I download the ISO, extract the application: still no problem.
I ask for a new DVD to be burned from the ISO: it works.
To this day, I claim "cosmic rays" caused the error.