BuddyPress.org

@flpagan Can you clarify whether you’re referring to the theme’s header or a default group’s or member’s profile header/ cover image?
If you’re referring to the theme’s header, please contact theme author.
If you’re referring to the cover images for groups or members, try this https://wordpress.org/plugins/buddypress-cover-photo/ – haven’t used it myself. Good luck.

@sjdeveloper delete BuddyPress plugin folder to remove the error first, it will bring the site live and afterword activate the default 2020 theme to disable any function call from the currently active theme which requires BuddyPress profile component. Install BuddyPress and enable the profile component then activate your theme again.

@socially2020 it will be your theme-specific customization task.

@scox1 it might be theme-specific, try to check with default theme at staging/development site.

@dmcsupport to debug try to disable all active plugin except BuddyPress and also toggle to the default 2020 theme.
It might be possible any of your active plugin or theme is using flush_rewrite_rules() and trying to set their own path.

@rootcr8r You can override single member profile template inside child theme

Template Hierarchy

/buddypress/members/single/ folder contain all files
https://github.com/buddypress/BuddyPress/tree/master/src/bp-templates/bp-legacy/buddypress/members/single

For private messages, auto-complete only shows your friends.
To access everyone, put this in your theme/functions.php or in plugins/bp-custom.php
define( 'BP_MESSAGES_AUTOCOMPLETE_ALL', true );

To customize the options provided by autocomplete, you would need to write some custom code.

You could always customize your own templates and change it to your behest.

You can get an idea about how to start it out here https://codex.buddypress.org/themes/theme-compatibility-1-7/a-quick-look-at-1-7-theme-compatibility/

From then on its just about coding it to your own set standards.

You could override the template to showcase your own unique one. Here’s some more info on it.

Theme Compatibility & Template Files

Exposing every aspect as an option is untenable.
You need to adjust a template file.
The file in question depends on which BP template pack you are using.
Go to wp-admin > Settings > BuddyPress > Options and note the setting for the Template Pack option.
If you are using Nouveau, then this is the file:
wp-content\plugins\buddypress\bp-templates\bp-nouveau\buddypress\activity\index.php

In that file, find this: <?php bp_get_template_part( 'activity/post-form' ); ?>
And change it to this:

<?php 
     if ( ! bp_is_user() ) {
         bp_get_template_part( 'activity/post-form' ); 
     }
?>

Note: it is recommended that you do not edit the template files in the BuddyPress plugin.
Your changes will be wiped out when you update the plugin on a new release.
Instead, create a template overload and then edit that file.
More info re template overloads:.