Uncaught Error: call_user_func_array(): Argument #1 ($callback) must be a valid callback, non-static method dc_jqsocialstream::header() cannot be called statically
in /var/www/html/web/wp/wp-includes/class-wp-hook.php on line 324

Call stack:

1. WP_Hook::apply_filters(NULL, array)
   wp-includes/class-wp-hook.php:348
2. WP_Hook::do_action(array)
   wp-includes/plugin.php:517
3. do_action('wp_head')
   wp-includes/general-template.php:3064
4. wp_head()
   app/themes/tbr-sub/templates/head.php:12
5. require('/var/www/html/web/ap...b/templates/head.php')
   wp-includes/template.php:812
6. load_template('/var/www/html/web/ap...b/templates/head.php', false, array)
   wp-includes/template.php:745
7. locate_template(array, true, false, array)
   wp-includes/general-template.php:206
8. get_template_part('templates/head')
   app/themes/tbr-sub/base.php:10
9. include('/var/www/html/web/app/themes/tbr-sub/base.php')
   wp-includes/template-loader.php:106
10. require_once('/var/www/html/web/wp.../template-loader.php')
    wp-blog-header.php:19
11. require('/var/www/html/web/wp/wp-blog-header.php')
    index.php:6