Mantis Bug Tracker - Forums

OS: Windows server 2008R2
XAMPP configuration running only mantisbt
current version 1.2.4 Yeah very old
installing version 2.15.0

Error message:
Warning: require_once(C:\xampp\htdocs\mantis\vendor/autoload.php): failed to open stream: No such file or directory in C:\xampp\htdocs\mantis\core.php on line 91

Fatal error: require_once(): Failed opening required 'C:\xampp\htdocs\mantis\vendor/autoload.php' (include_path='.;C:\xampp\php\PEAR') in C:\xampp\htdocs\mantis\core.php on line 91

I assume you did not download the official package, but just the source from Github.
https://www.mantisbt.org/download.php