Fatal error: Uncaught TypeError: call_user_func_array(): Argument #1 ($callback) must be a valid callback, function "my_register_sidebars" not found or invalid function name in /home/juliabel/unit4.juliabeltrameismyname.share.library.harvard.edu/wp-includes/class-wp-hook.php:292 Stack trace: #0 /home/juliabel/unit4.juliabeltrameismyname.share.library.harvard.edu/wp-includes/class-wp-hook.php(316): WP_Hook->apply_filters(NULL, Array) #1 /home/juliabel/unit4.juliabeltrameismyname.share.library.harvard.edu/wp-includes/plugin.php(484): WP_Hook->do_action(Array) #2 /home/juliabel/unit4.juliabeltrameismyname.share.library.harvard.edu/wp-includes/widgets.php(1799): do_action('widgets_init') #3 /home/juliabel/unit4.juliabeltrameismyname.share.library.harvard.edu/wp-includes/class-wp-hook.php(292): wp_widgets_init('') #4 /home/juliabel/unit4.juliabeltrameismyname.share.library.harvard.edu/wp-includes/class-wp-hook.php(316): WP_Hook->apply_filters(NULL, Array) #5 /home/juliabel/unit4.juliabeltrameismyname.share.library.harvard.edu/wp-includes/plugin.php(484): WP_Hook->do_action(Array) #6 /home/juliabel/unit4.juliabeltrameismyname.share.library.harvard.edu/wp-settings.php(560): do_action('init') #7 /home/juliabel/unit4.juliabeltrameismyname.share.library.harvard.edu/wp-config.php(106): require_once('/home/juliabel/...') #8 /home/juliabel/unit4.juliabeltrameismyname.share.library.harvard.edu/wp-load.php(37): require_once('/home/juliabel/...') #9 /home/juliabel/unit4.juliabeltrameismyname.share.library.harvard.edu/wp-blog-header.php(13): require_once('/home/juliabel/...') #10 /home/juliabel/unit4.juliabeltrameismyname.share.library.harvard.edu/index.php(17): require('/home/juliabel/...') #11 {main} thrown in /home/juliabel/unit4.juliabeltrameismyname.share.library.harvard.edu/wp-includes/class-wp-hook.php on line 292