Hello, I'm getting these warnings on some sections of ITF (ie clicking on a client when it opens the client's page). Any idea what could be triggering them?

Thanks!

Beginning of page:

Warning: mysqli_fetch_assoc() expects parameter 1 to be mysqli_result, bool given in /var/www/html/itflow/inc_all_client.php on line 198
Notice: Trying to access array offset on value of type null in /var/www/html/itflow/inc_all_client.php on line 200
Warning: mysqli_fetch_assoc() expects parameter 1 to be mysqli_result, bool given in /var/www/html/itflow/inc_all_client.php on line 210
Notice: Trying to access array offset on value of type null in /var/www/html/itflow/inc_all_client.php on line 212

End of page:

Warning: mysqli_num_rows() expects parameter 1 to be mysqli_result, bool given in/var/www/html/itflow/client_overview.phpon line146
Warning: mysqli_num_rows() expects parameter 1 to be mysqli_result, bool given in/var/www/html/itflow/client_overview.phpon line147
Warning: mysqli_num_rows() expects parameter 1 to be mysqli_result, bool given in/var/www/html/itflow/client_overview.phpon line148