@Igokul
I opened error_log file and found such errors....
[27-Nov-2020 11:59:34 UTC] WordPress database error Table 'mydatabase.wp_fs_accounts' doesn't exist for query SELECT COUNT(0) as `account_count` FROM wp_fs_accounts WHERE ((id IN (SELECT account_id FROM wp_fs_account_status)) OR (id IN (SELECT account_id FROM wp_fs_account_nodes WHERE id IN (SELECT node_id FROM wp_fs_account_node_status)))) made by require('wp-blog-header.php'), require_once('wp-load.php'), require_once('wp-config.php'), require_once('wp-settings.php'), include_once('/plugins/fs-poster/init.php'), FSPoster\App\Providers\Bootstrap->__construct, FSPoster\App\Providers\CronJob::init, FSPoster\App\Providers\CronJob::runBackgroundTaksIfNeeded
[27-Nov-2020 12:01:02 UTC] WordPress database error Table 'mydatabase.wp_fs_feeds' doesn't exist for query SELECT COUNT(0) as `feed_count` FROM `wp_fs_feeds` WHERE `share_on_background`=1 and `is_sended`=0 and `send_time`<='2020-11-27 17:01:02' made by require('wp-blog-header.php'), require_once('wp-load.php'), require_once('wp-config.php'), require_once('wp-settings.php'), include_once('/plugins/fs-poster/init.php'), FSPoster\App\Providers\Bootstrap->__construct, FSPoster\App\Providers\CronJob::init, FSPoster\App\Providers\CronJob::runBackgroundTaksIfNeeded
[27-Nov-2020 12:01:02 UTC] WordPress database error Table 'mydatabase.wp_fs_schedules' doesn't exist for query SELECT COUNT(0) as `schedule_count` FROM `wp_fs_schedules` WHERE `status`='active' and `next_execute_time`<='2020-11-27 17:01:02' made by require('wp-blog-header.php'), require_once('wp-load.php'), require_once('wp-config.php'), require_once('wp-settings.php'), include_once('/plugins/fs-poster/init.php'), FSPoster\App\Providers\Bootstrap->__construct, FSPoster\App\Providers\CronJob::init, FSPoster\App\Providers\CronJob::runBackgroundTaksIfNeeded
[27-Nov-2020 12:01:02 UTC] WordPress database error Table 'mydatabase.wp_fs_accounts' doesn't exist for query SELECT COUNT(0) as `account_count` FROM wp_fs_accounts WHERE ((id IN (SELECT account_id FROM wp_fs_account_status)) OR (id IN (SELECT account_id FROM wp_fs_account_nodes WHERE id IN (SELECT node_id FROM wp_fs_account_node_status)))) made by require('wp-blog-header.php'), require_once('wp-load.php'), require_once('wp-config.php'), require_once('wp-settings.php'), include_once('/plugins/fs-poster/init.php'), FSPoster\App\Providers\Bootstrap->__construct, FSPoster\App\Providers\CronJob::init, FSPoster\App\Providers\CronJob::runBackgroundTaksIfNeeded