[Warning] In read_cache after calling loadTemplate

[agboom]

Warning: unserialize(): Function spl_autoload_call() hasn't defined the class it was called for in h2o/loaders.php on line 108

I looked into it, but don't understand how unserialize() uses spl_autoload_call() and which class should be defined. In fact, I don't get the warning at all, because unserialize() is a global function, so why is there a need to define a class?

Full stack trace below. H2o version is 0.4.1.

( ! ) Warning: unserialize(): Function spl_autoload_call() hasn't defined the class it was called for in h2o/loaders.php on line 108
Call Stack
#	Time	Memory	Function	Location
1	0.0002	245648	{main}( )	../index.php:0
2	0.0118	1005480	H2o->__construct( )	../index.php:9
3	0.0123	1010792	H2o->loadTemplate( )	../h2o.php:85
4	0.0123	1010856	H2o_File_Loader->read_cache( )	../h2o.php:90
5	0.0134	1024048	unserialize ( )	../loaders.php:108

[unknown8063]

require H2O_ROOT.'h2o/parser.php'; needs to be added to line 13 of h2o.php