[php] Laravel Update Query

This error would suggest that User::where('email', '=', $userEmail)->first() is returning null, rather than a problem with updating your model.

Check that you actually have a User before attempting to change properties on it, or use the firstOrFail() method.

$UpdateDetails = User::where('email', $userEmail)->first();

if (is_null($UpdateDetails)) {
    return false;
}

or using the firstOrFail() method, theres no need to check if the user is null because this throws an exception (ModelNotFoundException) when a model is not found, which you can catch using App::error() http://laravel.com/docs/4.2/errors#handling-errors

$UpdateDetails = User::where('email', $userEmail)->firstOrFail();