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 /customers/4/b/6/shadowart.se/httpd.www/wp-content/plugins/jetpack/class.jetpack-sync.php:47
Stack trace:
#0 /customers/4/b/6/shadowart.se/httpd.www/wp-content/plugins/jetpack/modules/enhanced-distribution.php(12): Jetpack_Sync::sync_posts('/customers/4/b/...')
#1 /customers/4/b/6/shadowart.se/httpd.www/wp-content/plugins/jetpack/class.jetpack.php(1142): require('/customers/4/b/...')
#2 /customers/4/b/6/shadowart.se/httpd.www/wp-includes/plugin.php(496): Jetpack::load_modules('')
#3 /customers/4/b/6/shadowart.se/httpd.www/wp-settings.php(237): do_action('plugins_loaded')
#4 /customers/4/b/6/shadowart.se/httpd.www/wp-config.php(90): require_once('/customers/4/b/...')
#5 /customers/4/b/6/shadowart.se/httpd.www/wp-load.php(37): require_once('/customers/4/b/...')
#6 /customers/4/b/6/shadowart.se/httpd.www/wp-blog-header.php(12): require_once('/customers/4/b/...')
#7 /customers/4/b/6/shadowart.se/httpd.www/index.php(17): require('/customers/4/b/...')
#8 {main}
  thrown in /customers/4/b/6/shadowart.se/httpd.www/wp-content/plugins/jetpack/class.jetpack-sync.php on line 47