What are potential pitfalls when upgrading PHP versions in existing code?

When upgrading PHP versions in existing code, potential pitfalls include deprecated functions or features that may no longer work, changes in syntax or behavior that could break existing code, and compatibility issues with third-party libraries or frameworks. To mitigate these risks, it is important to thoroughly test the code after the upgrade, update any deprecated functions or features, and make necessary changes to ensure compatibility with the new PHP version. 

// Example code snippet demonstrating how to update deprecated function in PHP
// Deprecated function: mysql_connect()
// Updated function: mysqli_connect()

// Deprecated code
$connection = mysql_connect('localhost', 'username', 'password');

// Updated code
$connection = mysqli_connect('localhost', 'username', 'password');

Keywords

backward compatibility deprecated functions syntax errors incompatible extensions performance degradation

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