Can you explain the purpose of your post ?
"File not found" is not the same as "404 Not Found"
Beyond that, I can't answer. But the suggestion is that there may be a vulnerability.
I also replied to your private inquiries thread, but again I'm not sure what the issue is here.
The unintended behaviors have been resolved. Thanks for the report and the explanation, Clumsy, HLFadmin and codedude.