What are the potential issues when upgrading from PHP 5.2 to PHP 5.3?

One potential issue when upgrading from PHP 5.2 to PHP 5.3 is the deprecation of the "call-time pass-by-reference" feature, where functions could be called with parameters passed by reference without explicitly specifying it in the function definition. To solve this, you need to remove the "&" symbol from the function call and update the function definition to include the "&" symbol before the parameter name.

// Before PHP 5.3
function myFunction(&$param) {
    // function logic
}

$var = "value";
myFunction(&$var);

// After PHP 5.3
function myFunction(&$param) {
    // function logic
}

$var = "value";
myFunction($var);