Constant Error customising

For some reason this is constantly showing up on my dashboard and before the theme loads in the customising page, The header is uncustomisable, it keeps telliing me theres an update error, do assist, this theme is beautiful and I’d like to purchase the pro if you can solve this issue

Warning: Cannot modify header information – headers already sent by (output started at /home2/shockbulb/finnfirestudios.com/wp-content/themes/elitepress/functions/customizer/customizer-blog.php:40) in /home2/shockbulb/finnfirestudios.com/wp-admin/includes/misc.php on line 1116

Warning: Cannot modify header information – headers already sent by (output started at /home2/shockbulb/finnfirestudios.com/wp-content/themes/elitepress/functions/customizer/customizer-blog.php:40) in /home2/shockbulb/finnfirestudios.com/wp-includes/option.php on line 919

Warning: Cannot modify header information – headers already sent by (output started at /home2/shockbulb/finnfirestudios.com/wp-content/themes/elitepress/functions/customizer/customizer-blog.php:40) in /home2/shockbulb/finnfirestudios.com/wp-includes/option.php on line 920