Re: Getting Fatal Errors while Installing buddypress on WordPress single user
First of all, we may need more information. If what I suggest below does not resolve your issue, then please answer these questions: https://buddypress.org/community/groups/how-to-and-troubleshooting/forum/topic/when-asking-for-support/
The error message that you have posted is strange. BuddyPress does not have a file called bp-cores.php. You mentioned that you made some file modifications. Did you open up the file bp-loader.php? I would look in that file on line 19 to see if you accidentally added an “s” to bp-core. Line 19 should read:
require_once( WP_PLUGIN_DIR . '/buddypress/bp-core.php' );
If you see that there is an “s” but you are sure that you did not change it yourself, I would suggest deactivating then deleting BuddyPress. Then redownload BuddyPress and reinstall. Make sure your are downloading BuddyPress from this site
Finally, when trying to debug BuddyPress, always use the default theme and deactivate all other plugins. You need to isolate what is happening within BuddyPress.