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Class __PHP_Incomplete_Class has no unserializer #4571
i updated to the latest version of WordPress and got the following error -
Warning: Class __PHP_Incomplete_Class has no unserializer in /home/content/p3pnexwpnas14_data02/95/3039995/html/wp-content/object-cache.php on line 520
the problem was only occuring one www verion of the site not the non-www
When we deactivated Yoast the error stopped appearing .. we have seen this fix the error for quite a number of people -however i still want to use Yoast rather find another plugin.
this site is being run under managed wordpress hosing with Media Temple.
From one of the WP engineers:
"This is caused by a plugin storing an instance of a class into Memcache
When the value is retrieved from the cache, and the class is no longer
It's not a bug in WordPress as such, but rather in whatever is storing the
So I think this is related to the new sitemap cache implementation, but I only seen it once myself and it disappeared immediately from cache flush. I don't have a good guess on what possibly causes it.
I am familiar with issue in general, but since we autoload all classes in plugin it would be very strange for any of them to be unavailable.
Could you please elaborate about your setup? Do you serve site on two different URLs?
There are a solution and more details information on this thread about this issue: https://wordpress.org/support/topic/error-warning-class-_php_incomplete_class-has-no-unserializer
I can tell you an easy way to reproduce one of scenarios where this errors appears:
We are using this tool for deploying from staging to live website, and as you can imagine it's not working anymore.
I mentioned dry run just because it's quickest way to get this error and it's easy to test because it doesn't save changes in database. It will still load serialized string and fail with replace action because it triggers
referenced this issue
Jul 8, 2016
@iamzik Thanks for your answer.