BuddyPress.org

The user_id argument doesn’t exist because there is no user_id argument. The argument that accepts a user id is the item_id argument as I stated above. Try this:

echo bp_core_fetch_avatar( array( ‘width’ => 30, ‘height’ => 30, ‘item_id’ => 1 ) );

If all you need is the thumbnail, then you don’t need the ‘type’ argument, as it defaults to thumbnail.