warning code: class php incomplete message

Occasionally we get this message across the top of the site.  And then it goes away.  Any idea what causes it and how to remove?  The site is a wordpress site using genesis framework.  I also attached a screen shot.  This happens on phones and desktops.

Warning: Class __PHP_Incomplete_Class has no unserializer in /home/content/a2pnexwpnas04_data01/40/3310340/html/wp-content/object-cache.php on line 894

Warning: Cannot modify header information - headers already sent by (output started at /home/content/a2pnexwpnas04_data01/40/3310340/html/wp-content/object-cache.php:894) in /home/content/a2pnexwpnas04_data01/40/3310340/html/wp-content/plugins/planso-forms/libs/wp-session-manager/class-wp-session.php on line 124
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Ray PaseurCommented:
The second part about the header information Warning is caused by the first part.  Some explanation here:

The first part seems to be well-documented on the WordPress site.

The most common solution seems to go something like this: "In the wp-content folder just rename object-cache.php to object-cache.php.BAK or anything else and that’s it."

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nsitedesignsAuthor Commented:
Will give it a shot.  I also have godaddy managed wordpress for hosting as do some of the people in the wordpress.org link and have run across caching issues when updating site.  I wonder if they are the problem?  

p.s.  Can't try your solution until client calls me.  they have 2-step verification in place for host and I cannot login without the 4 digit code that gets texted.  What a pain!
nsitedesignsAuthor Commented:
OK.  I got in.  Interestingly enough there are 3 object-cache files.  Would you recommend I rename or delete the other two (.redis or .apc)?

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Ray PaseurCommented:
Redis and APC are cache systems, independent of WP object-cache, but used by WP extensions to provide a cache.  My first instinct is to disable all of them via a rename, as described on WordPress.org.  But they may be providing a useful service (or trying to) in the form of higher performance.  So it might be good to understand how cache works and keep an eye on the site to see if you need to address performance issues after these are disabled.  Probably Redis is the more promising approach.

More information on cache, in general:

Information about APC:

Information about Redis (looks better than the APC):
nsitedesignsAuthor Commented:
Thanks Ray!
Ray PaseurCommented:
Glad to help -- I hope this fixes things!
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