__PHP_Incomplete_Class_Name wrong

Question

We\'re randomly getting some very strange error logs. They don\'t happen on every page hit, even with the same parameters/actions/etc, and they don\'t seem repeatable, each

Answer 1

As written in the quote in your question __PHP_Incomplete_Class_Name is a special class name in PHP that is used whenever the class definition could not be found when unserializing (unserialize()).

It's suggested to either ensure the class definition is available or to provide some autoloading for the missing class.

You commented that PHP is looking for the wrong classname here:

wrong: LoginLogging
right: ScormElement

It's hard to say with the information given why the classname is being changed on serialization/unserialization. The information you've given (especially the dump) in your question is incomplete.

So the options are limited to some general suggestions:

You could inspect the serialized string which classname is given in there so you could at least say if it happens with serialization or unserialization. You can easily inspect serialized data with the Serialized PHP Library which has a text-dumper for debug purposes.

Additionally there is the unserialize_callback_func Ini-Directive you can use to further trace the problem.

<?php
$serialized_object='O:1:"a":1:{s:5:"value";s:3:"100";}';

// unserialize_callback_func directive available as of PHP 4.2.0
ini_set('unserialize_callback_func', 'mycallback'); // set your callback_function

function mycallback($classname) 
{
    // just include a file containing your classdefinition
    // you get $classname to figure out which classdefinition is required
}

As you write the problem does not occur any longer, I suspect that at some point the serialization on your site was broken storing invalid data. Which framework/libraries/application are you using? Which component takes care about serialization?

Answer 2

Are you, by any chance, using some opcode cache (e.g. APC, XCache) or some debugger? They sometimes cause weird things to happen. If there isn't and never was a LoginLogging class in your project, but yours is not the only project on the server, I would bid on the cache.

Answer 3

If your trying to access a property method of an object or serialized value you've stored in a $_SESSION variable and you included the class after calling session_start() try including the class before calling session_start();

Answer 4

It is the serialization issue in your code.It may be your code for some reason could not initialize the object and in next part of your code tries to convert that object to string or some other data type.

Just inspect your code, properly initialize your objects.

Check if you are using serialize()/unserialize() method.