This is still not clear whether or not you have an issue in your environment causing this error or not. I can say we have tested the latest version of the plugin and are not able to reproduce the error in a standard wordpress / woocommerce environment.
Here’s some more information from our dev team:
The code indicated in the error message has to do with the MyStyle session that the plugin is using to track the user. To get the session, it first looks in php’s built in $_SESSION and if it’s not in there, it looks in the user’s cookies for a session id and rebuilds the session object by pulling session data from the db (using the session id).
This specific error is:
“The script tried to execute a method or access a property of an incomplete object”.
We’ve never seen this error before. I’m guessing that it has to do with trying to build the object from the $_SESSION and that the data coming back from $_SESSION is somehow corrupt.
One idea is to clear all session data in case for some reason there is corrupted session data from other plugins (you would most likely need ssh access to the server to do this).
This post seems relevant: https://stackoverflow.com/questions/1055728/php-session-with-an-incomplete-object
We’re still doing more investigation, but I may need access to your site to pinpoint the issue if it’s not with our plugin code.