Navigation Links Return 404 Errors
A common error after installation of BuddyPress from within the WordPress admin panel is to not set pretty permalinks. If you fail to do this then all of the links in the header will return 404 errors.
To fix this problem, enter the WordPress admin panel > Settings > Pemalinks – set to any configuration other than the default configuration. The mod_rewrite must be enabled on your server for pretty permalinks to work.