I have a wordpress MU (3.0.1) setup (upgraded from 2.9.2).

It runs on 4 instances, load balanced, and all 4 connect to same database.

Now, when only one instance is running, it is working fine...

When I run multiple instances, I am not able to trash or undo trash or even do any change in settings .. I get this message:

Are you sure you want to do this?

Please try again.

the URL when this occurs is


What could be the issue and how to fix it?


Likely this is result of check_admin_referer() function not recognizing your request as coming from admin area. Since your query clearly contains nonce it is likely what is not being recognized.

Nonces can be locked down in many ways. They are unique to the WordPress install, to the WordPress user, to the action, to the object of the action, and to the time of the action (24 hour window). That means that if any of these things changes, the nonce is invalid. ( Mark Jaquith )

My theory is that your load-balanced installs don't count as same install for the purpose of generating nonce. If possible try to limit admin area to single server and see if that helps.

  • <pre>"GET /myblog/wp-admin/post.php?post=44&action=trash&_wpnonce=12ec38a4a9 HTTP/1.1" 403 1319 "mysite/myblogs/wp-admin/…" </pre> Here, I see that refer is being sent properly ... – Ramprasad Prabhakar Sep 16 '10 at 15:44
  • check_admin_referer() despite its name also checks nonce value, which is completely independent from HTTP protocol – Rarst Sep 16 '10 at 16:02
  • 2
    Thanks for the pointer. It looks like the config across the LB nodes were not the same. nonce_salt was not uniform and once all the config were made the same, the issue was resolved. – Ramprasad Prabhakar Sep 16 '10 at 16:05
  • Consider "sticky sessions" with your load balancing. – hakre Sep 16 '10 at 21:32

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