Warning: Creating default object from empty value

Warning: Creating default object from empty value in /home/fumahtay/public_html/tuts/wp-content/plugins/coursepress/includes/classes/class.shortcodes.php on line 3088
Warning: array_key_exists(): The first argument should be either a string or an integer in /home/fumahtay/public_html/tuts/wp-includes/cache.php on line 672
Warning: array_key_exists(): The first argument should be either a string or an integer in /home/fumahtay/public_html/tuts/wp-includes/cache.php on line 672
Warning: array_key_exists(): The first argument should be either a string or an integer in /home/fumahtay/public_html/tuts/wp-includes/cache.php on line 672

and i have so many problems with plugin can you help me