Unknown Named Parameter

Why This Happens

PHP 8.0 introduced named arguments, but the names must exactly match the parameter names in the function definition. This error occurs when there is a typo, the parameter was renamed, or you are using the wrong name for a built-in function's parameter.

The Problem

function createButton(string $label, string $color = 'blue'): string {
    return "<button style='color:$color'>$label</button>";
}
echo createButton(label: 'Click', colour: 'red'); // 'colour' not 'color'

The Fix

function createButton(string $label, string $color = 'blue'): string {
    return "<button style='color:$color'>$label</button>";
}
echo createButton(label: 'Click', color: 'red');

Step-by-Step Fix

1. 1

   Check the parameter name

   Compare the named argument in your call with the actual parameter name in the function definition. Look for spelling differences.

2. 2

   Verify the function signature

   Check the function or method definition, including inherited or interface methods, to see the exact parameter names.

3. 3

   Fix the argument name

   Correct the named argument to match the parameter name exactly.