I don't think it's a change in OO handling, maybe it's a change in the
error_reporting level for the new version and you hadn't noticed the
problem before.
Its a Fatel Error not a warning. Dont see how level off error
reporting could be relevant.
Fair enough :P
What type of variable is 'cart' when this error happens?
Have permissions been screwed on the session_save_path folder? (check a phpinfo for where this is if you're not setting it explicitly).
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