What are the potential causes of the "Invalid argument supplied for foreach()" error in PHP?

The "Invalid argument supplied for foreach()" error in PHP occurs when you try to iterate over a variable that is not an array or an object that implements the Traversable interface. To solve this issue, you should check if the variable is an array or an object before using foreach loop to iterate over it.

// Check if the variable is an array before using foreach loop
if (is_array($variable)) {
    foreach ($variable as $item) {
        // Your code here
    }
} else {
    // Handle the case where the variable is not an array
}