The forbidden file format

when i add file in my topic this error is showing "The forbidden file format" please guide me please help me experts

rename file else upper registr EXT -> ext lower registr

adust, want to add prov file?? how can i add prov file in my topic please help me

there is the array of extensions you can upload. so you need to add your ext. in this list. See the file forum/index.php