Error trying to login to WordPress

I have a lengthy error message when trying to login to WordPress to edit my website. I’m not very au fait with the technical side of WordPress so, if anyone can help me, please be gentle!

I have access to file manager so would be able to make amends if I knew what to put!

There’s an error message on the actual website too which is:
Warning: Creating default object from empty value in /customers/d/f/b/trabolganbirds.com/httpd.www/wp-content/themes/Avada-3/includes/avadaredux/avadaredux-framework/AvadaReduxCore/inc/class.avadaredux_filesystem.php on line 29

The error when trying to access the WordPress admin is:
Warning: Creating default object from empty value in /customers/d/f/b/trabolganbirds.com/httpd.www/wp-content/themes/Avada-3/includes/avadaredux/avadaredux-framework/AvadaReduxCore/inc/class.avadaredux_filesystem.php on line 29 Warning: Cannot modify header information – headers already sent by (output started at /customers/d/f/b/trabolganbirds.com/httpd.www/wp-content/themes/Avada-3/includes/avadaredux/avadaredux-framework/AvadaReduxCore/inc/class.avadaredux_filesystem.php:29) in /customers/d/f/b/trabolganbirds.com/httpd.www/wp-login.php on line 521 Warning: Cannot modify header information – headers already sent by (output started at /customers/d/f/b/trabolganbirds.com/httpd.www/wp-content/themes/Avada-3/includes/avadaredux/avadaredux-framework/AvadaReduxCore/inc/class.avadaredux_filesystem.php:29) in /customers/d/f/b/trabolganbirds.com/httpd.www/wp-login.php on line 537 Warning: Cannot modify header information – headers already sent by (output started at /customers/d/f/b/trabolganbirds.com/httpd.www/wp-content/themes/Avada-3/includes/avadaredux/avadaredux-framework/AvadaReduxCore/inc/class.avadaredux_filesystem.php:29) in /customers/d/f/b/trabolganbirds.com/httpd.www/wp-includes/functions.php on line 6274 Warning: Cannot modify header information – headers already sent by (output started at /customers/d/f/b/trabolganbirds.com/httpd.www/wp-content/themes/Avada-3/includes/avadaredux/avadaredux-framework/AvadaReduxCore/inc/class.avadaredux_filesystem.php:29) in /customers/d/f/b/trabolganbirds.com/httpd.www/wp-includes/pluggable.php on line 987 Warning: Cannot modify header information – headers already sent by (output started at /customers/d/f/b/trabolganbirds.com/httpd.www/wp-content/themes/Avada-3/includes/avadaredux/avadaredux-framework/AvadaReduxCore/inc/class.avadaredux_filesystem.php:29) in /customers/d/f/b/trabolganbirds.com/httpd.www/wp-includes/pluggable.php on line 988 Warning: Cannot modify header information – headers already sent by (output started at /customers/d/f/b/trabolganbirds.com/httpd.www/wp-content/themes/Avada-3/includes/avadaredux/avadaredux-framework/AvadaReduxCore/inc/class.avadaredux_filesystem.php:29) in /customers/d/f/b/trabolganbirds.com/httpd.www/wp-includes/pluggable.php on line 989 Warning: Cannot modify header information – headers already sent by (output started at /customers/d/f/b/trabolganbirds.com/httpd.www/wp-content/themes/Avada-3/includes/avadaredux/avadaredux-framework/AvadaReduxCore/inc/class.avadaredux_filesystem.php:29) in /customers/d/f/b/trabolganbirds.com/httpd.www/wp-includes/pluggable.php on line 990 Warning: Cannot modify header information – headers already sent by (output started at /customers/d/f/b/trabolganbirds.com/httpd.www/wp-content/themes/Avada-3/includes/avadaredux/avadaredux-framework/AvadaReduxCore/inc/class.avadaredux_filesystem.php:29) in /customers/d/f/b/trabolganbirds.com/httpd.www/wp-includes/pluggable.php on line 991 Warning: Cannot modify header information – headers already sent by (output started at /customers/d/f/b/trabolganbirds.com/httpd.www/wp-content/themes/Avada-3/includes/avadaredux/avadaredux-framework/AvadaReduxCore/inc/class.avadaredux_filesystem.php:29) in /customers/d/f/b/trabolganbirds.com/httpd.www/wp-includes/pluggable.php on line 992 Warning: Cannot modify header information – headers already sent by (output started at /customers/d/f/b/trabolganbirds.com/httpd.www/wp-content/themes/Avada-3/includes/avadaredux/avadaredux-framework/AvadaReduxCore/inc/class.avadaredux_filesystem.php:29) in /customers/d/f/b/trabolganbirds.com/httpd.www/wp-includes/pluggable.php on line 995 Warning: Cannot modify header information – headers already sent by (output started at /customers/d/f/b/trabolganbirds.com/httpd.www/wp-content/themes/Avada-3/includes/avadaredux/avadaredux-framework/AvadaReduxCore/inc/class.avadaredux_filesystem.php:29) in /customers/d/f/b/trabolganbirds.com/httpd.www/wp-includes/pluggable.php on line 996 Warning: Cannot modify header information – headers already sent by (output started at /customers/d/f/b/trabolganbirds.com/httpd.www/wp-content/themes/Avada-3/includes/avadaredux/avadaredux-framework/AvadaReduxCore/inc/class.avadaredux_filesystem.php:29) in /customers/d/f/b/trabolganbirds.com/httpd.www/wp-includes/pluggable.php on line 999 Warning: Cannot modify header information – headers already sent by (output started at /customers/d/f/b/trabolganbirds.com/httpd.www/wp-content/themes/Avada-3/includes/avadaredux/avadaredux-framework/AvadaReduxCore/inc/class.avadaredux_filesystem.php:29) in /customers/d/f/b/trabolganbirds.com/httpd.www/wp-includes/pluggable.php on line 1000 Warning: Cannot modify header information – headers already sent by (output started at /customers/d/f/b/trabolganbirds.com/httpd.www/wp-content/themes/Avada-3/includes/avadaredux/avadaredux-framework/AvadaReduxCore/inc/class.avadaredux_filesystem.php:29) in /customers/d/f/b/trabolganbirds.com/httpd.www/wp-includes/pluggable.php on line 1001 Warning: Cannot modify header information – headers already sent by (output started at /customers/d/f/b/trabolganbirds.com/httpd.www/wp-content/themes/Avada-3/includes/avadaredux/avadaredux-framework/AvadaReduxCore/inc/class.avadaredux_filesystem.php:29) in /customers/d/f/b/trabolganbirds.com/httpd.www/wp-includes/pluggable.php on line 1002 Warning: Cannot modify header information – headers already sent by (output started at /customers/d/f/b/trabolganbirds.com/httpd.www/wp-content/themes/Avada-3/includes/avadaredux/avadaredux-framework/AvadaReduxCore/inc/class.avadaredux_filesystem.php:29) in /customers/d/f/b/trabolganbirds.com/httpd.www/wp-includes/pluggable.php on line 1005 Warning: Cannot modify header information – headers already sent by (output started at /customers/d/f/b/trabolganbirds.com/httpd.www/wp-content/themes/Avada-3/includes/avadaredux/avadaredux-framework/AvadaReduxCore/inc/class.avadaredux_filesystem.php:29) in /customers/d/f/b/trabolganbirds.com/httpd.www/wp-includes/pluggable.php on line 1006 Warning: Cannot modify header information – headers already sent by (output started at /customers/d/f/b/trabolganbirds.com/httpd.www/wp-content/themes/Avada-3/includes/avadaredux/avadaredux-framework/AvadaReduxCore/inc/class.avadaredux_filesystem.php:29) in /customers/d/f/b/trabolganbirds.com/httpd.www/wp-includes/pluggable.php on line 1007 Warning: Cannot modify header information – headers already sent by (output started at /customers/d/f/b/trabolganbirds.com/httpd.www/wp-content/themes/Avada-3/includes/avadaredux/avadaredux-framework/AvadaReduxCore/inc/class.avadaredux_filesystem.php:29) in /customers/d/f/b/trabolganbirds.com/httpd.www/wp-includes/pluggable.php on line 1008 Warning: Cannot modify header information – headers already sent by (output started at /customers/d/f/b/trabolganbirds.com/httpd.www/wp-content/themes/Avada-3/includes/avadaredux/avadaredux-framework/AvadaReduxCore/inc/class.avadaredux_filesystem.php:29) in /customers/d/f/b/trabolganbirds.com/httpd.www/wp-includes/pluggable.php on line 1011

Thank you in advance!
Tish

The page I need help with: [log in to see the link]