Hello - I have done a manual upgrade of wordpress and am getting this error, for both the query.php and option.php pages.
If I replace all the files/folders in the wp-includes directory, with clean versions from the install, then my site appears as normal. But after a few minutes or sometimes several, the error comes up again.
Any ideas on what might be the issue(s)? Let me know if there's anything I can do to correct the problem.