Cannot modify header information – headers already sent

How to solve modify header PHP ERROR? I see this error more that one year
Website yan chen wu guan com (delete spaces)

Cannot modify header information – headers already sent: (33)
litespeed-cache/src/optimize.cls.php (line: 677)
litespeed-cache/src/optimize.cls.php (Line: 678)
litespeed-cache/src/purge.cls.php (line: 523)

Header may not contain NUL bytes:
litespeed-cache/src/core.cls.php (line: 721)
litespeed-cache/src/tag.cls.php (line: 124)

litespeed-cache/src/cloud.cls.php (Line: 1882)

[Message]:

Uncaught exception: failed to fetch quic.cloud whitelist curl error 28: resolving timed out after 5001 milliseconds in /var/www/html/wp-content/plugins/litespeed-cache/src/cloud.cls.php:1882 stack trace: #0 /var/www/html/wp-content/plugins/litespeed-cache/src/cloud.cls.php(1838): litespeed\cloud->_update_ips() #1 /var/www/html/wp-content/plugins/litespeed-cache/src/rest.cls.php(142): litespeed\cloud->is_from_cloud() #2 /var/www/html/wp-includes/rest-api/class-wp-rest-server.php(1259): litespeed\rest->is_from_cloud() #3 /var/www/html/wp-includes/rest-api/class-wp-rest-server.php(1125): wp_rest_server->respond_to_request() #4 /var/www/html/wp-includes/rest-api/class-wp-rest-server.php(439): wp_rest_server->dispatch() #5 /var/www/html/wp-includes/rest-api.php(459): wp_rest_server->serve_request() #6 /var/www/html/wp-includes/class-wp-hook.php(324): rest_api_loaded() #7 /var/www/html/wp-includes/class-wp-hook.php(348): wp_hook->apply_filters() #8 /var/www/html/wp-includes/plugin.php(565): wp_hook->do_action() #9 /var/www/html/wp-includes/class-wp.php(418): do_action_ref_array() #10 /var/www/html/wp-includes/class-wp.php(818): wp->parse_request() #11 /var/www/html/wp-includes/functions.php(1342): wp->main() #12 /var/www/html/wp-blog-header.php(16): wp() #13 /var/www/html/index.php(17): require('...') #14 {main} thrown