Fatal error: Uncaught TypeError: call_user_func_array(): Argument #1 ($callback) must be a valid callback, first array member is not a valid class name or object in /home/www/professorphd.com/wp-content/plugins/jetpack/class.jetpack-sync.php:47
Stack trace:
#0 /home/www/professorphd.com/wp-content/plugins/jetpack/modules/enhanced-distribution.php(12): Jetpack_Sync::sync_posts('/home/www/profe...')
#1 /home/www/professorphd.com/wp-content/plugins/jetpack/class.jetpack.php(1142): require('/home/www/profe...')
#2 /home/www/professorphd.com/wp-includes/class-wp-hook.php(307): Jetpack::load_modules('')
#3 /home/www/professorphd.com/wp-includes/class-wp-hook.php(331): WP_Hook->apply_filters(NULL, Array)
#4 /home/www/professorphd.com/wp-includes/plugin.php(474): WP_Hook->do_action(Array)
#5 /home/www/professorphd.com/wp-settings.php(450): do_action('plugins_loaded')
#6 /home/www/professorphd.com/wp-config.php(90): require_once('/home/www/profe...')
#7 /home/www/professorphd.com/wp-load.php(50): require_once('/home/www/profe...')
#8 /home/www/professorphd.com/wp-blog-header.php(13): require_once('/home/www/profe...')
#9 /home/www/professorphd.com/index.php(17): require('/home/www/profe...')
#10 {main}
thrown in /home/www/professorphd.com/wp-content/plugins/jetpack/class.jetpack-sync.php on line 47