TypeError: Wrong Return Type

Why This Happens

When a function declares a return type like : User, PHP enforces that the returned value matches. Returning null from a non-nullable return type or returning the wrong type triggers this error. This is common with find/lookup methods that may not find a result.

The Problem

function findUser(int $id): User {
    $user = $this->repository->find($id);
    return $user; // Returns null when not found
}

The Fix

function findUser(int $id): ?User {
    return $this->repository->find($id);
}

// Or throw an exception:
function findUserOrFail(int $id): User {
    $user = $this->repository->find($id);
    if ($user === null) {
        throw new NotFoundException("User $id not found");
    }
    return $user;
}

Step-by-Step Fix

1. 1

   Check the return type declaration

   Look at the function signature to see what return type is declared and compare it with what is actually being returned.

2. 2

   Determine if null is valid

   Decide whether the function should legitimately return null. If so, add ? to make the return type nullable.

3. 3

   Handle the missing value

   If null is not valid, add a check before returning and throw a descriptive exception when the expected value is not found.