I have a site on my aws server with PHP 7.1 and nginx as server for php. Wordpress latest version is running. Many time about after every 20 minutes I saw 502 error while accessing the site. Nginx server logs shows the following warnings.
*674241 FastCGI sent in stderr: "m_display_calc' in wp-content/plugins/ubermenu/includes/menuitems/UberMenuItem.class.php on line 563
PHP message: PHP Warning: Cannot assign an empty string to a string offset in wp-content/plugins/ubermenu/includes/menuitems/UberMenuItem.class.php on line 563
PHP message: PHP Warning: Illegal string offset 'item_display_calc' in wp-content/plugins/ubermenu/includes/menuitems/UberMenuItem.class.php on line 673
PHP message: PHP Warning: Illegal string offset 'item_display_calc' in wp-content/plugins/ubermenu/includes/menuitems/UberMenuItem.class.php on line 563
PHP message: PHP Warning: Cannot assign an empty string to a string offset in wp-content/plugins/ubermenu/includes/menuitems/UberMenuItem.class.php on line 563
PHP message: PHP Warning: Illegal string offset 'item_display_calc' in wp-content/plugins/ubermenu/includes/menuitems/UberMenuItem.class.php on line 673
PHP message: PHP Warning: Illegal string offset 'submenu_type_calc' in wp-content/plugins/ubermenu/includes/menuitems/UberMenuItem.class.php on line 371
PHP message: PHP Warning: Illegal string offset 'item_display_calc' in wp-content/plugins/ubermenu/includes/menuitems/UberMenuItem.class.php on line 563
PHP message: PHP Warning: Cannot assign an empty string to a string offset in wp-content/plugins/ubermenu/includes/menuitems/UberMenuItem.class.php on line 563
PHP message: PHP Warning: Illegal string offset 'item_display_calc' in wp-content/plugins/ubermenu/includes/menuitems/UberMenuItem.class.php on line 673
PHP message: PHP Warning: Illegal string offset 'item_display_calc' in wp-content/plugins/ubermenu/includes/menuitems/UberMenuItem.class.php on line 563
After simple googling I got this file: http://sevenspark.com/docs/ubermenu-3/faqs/php-7-1-warnings after which error still the same.
Please provide some useful solution, thanks