Sorry for jumping into this "old thread " but I am a total noob and I have installed the windows version of Mantis (V2.10.0) with the Bitnami installer and I am having the same issue. It appears the issue has been cropping up on some users throughout the years.
Everything installs fine and when one tries to launch the program,
Not Found. The requested URL /mantis/admin/install.php was not found on this server.
instead it seems to go straight to the installer.
Trying to get into mantis through 127.0.0.1/ yields the same result.
I just want to be able to log and track bugs (which is one of Mantis features I have read) but I am a total newbie with this type of software so I might be way out of my depth trying to run it.
some help would be appreciated