The error is self explanatory: the variable
$conn
does not exist.
The code you show only uses
$conn
- it does not at any point declare it and assign it a value:
$stmt = $conn->prepare("SELECT * FROM Clients WHERE CUID = :cuid");
$stmt = $conn->prepare("SELECT * FROM SubUser WHERE SubUsrID = :cuid");
$stmt = $conn->prepare("SELECT * FROM BervEmp WHERE BerEmpID = :cuid");
Those are the only references to it at all ...