Tried var_dump, is this any help?
NULL NULL array(3) refcount(2){ [“className”]=> string(54) “wpsolr\core\classes\engines\WPSOLR_AbstractIndexClient” refcount(1) [“file_name”]=> string(146) “/home/nginx/domains/foodlovers.xyz/public/wp-content/plugins/wpsolr-search-engine/wpsolr/core/classes/engines/class-wpsolr-abstractindexclient.php” refcount(2) [“base_name”]=> string(32) “class-wpsolr-abstractindexclient” refcount(2) } #0 wpsolr\core\classes\engines\sayHello() called at [/home/nginx/domains/foodlovers.xyz/public/wp-content/plugins/wpsolr-search-engine/wpsolr/core/classes/engines/class-wpsolr-abstractindexclient.php:1306] #1 require_once(/home/nginx/domains/foodlovers.xyz/public/wp-content/plugins/wpsolr-search-engine/wpsolr/core/classes/engines/class-wpsolr-abstractindexclient.php) called at [/home/nginx/domains/foodlovers.xyz/public/wp-content/plugins/wpsolr-search-engine/wpsolr/core/class-wpsolr-autoloader.php:37] #2 wpsolr\WPSOLR_Autoloader::Load(wpsolr\core\classes\engines\WPSOLR_AbstractIndexClient) #3 spl_autoload_call(wpsolr\core\classes\engines\WPSOLR_AbstractIndexClient) called at [/home/nginx/domains/foodlovers.xyz/public/wp-content/plugins/wpsolr-search-engine/wpsolr/core/dashboard/dashboard_operations.inc.php:36] #4 include(/home/nginx/domains/foodlovers.xyz/public/wp-content/plugins/wpsolr-search-engine/wpsolr/core/dashboard/dashboard_operations.inc.php) called at [/home/nginx/domains/foodlovers.xyz/public/wp-content/plugins/wpsolr-search-engine/wpsolr/core/dashboard/dashboard.php:418] #5 fun_set_solr_options() called at [/home/nginx/domains/foodlovers.xyz/public/wp-includes/class-wp-hook.php:286] #6 WP_Hook->apply_filters(, Array ([0] => )) called at [/home/nginx/domains/foodlovers.xyz/public/wp-includes/class-wp-hook.php:310] #7 WP_Hook->do_action(Array ([0] => )) called at [/home/nginx/domains/foodlovers.xyz/public/wp-includes/plugin.php:465] #8 do_action(toplevel_page_solr_settings) called at [/home/nginx/domains/foodlovers.xyz/public/wp-admin/admin.php:253]