I had recently noticed when testing Wordpress 4.0 upgrade, that it logged out of the site and went to the login screen, with a message saying to log back in to enjoy the new improved Wordpress.

What is the reason for this logout? I don't remember seeing this previously, and when a programmatically-called Wordpress upgrade occurs the user isn't logged out and it works fine.

  • Wasn't that obvious? What mark said below.
    – Robert hue
    Commented Sep 9, 2014 at 5:37
  • No, it would be obvious if there were a technical limitation or breakage with upgrade, but like I said a programmatically-called wp upgrade didn't ruin my current logged-in session. - so why does wp update mechanism log you out?
    – NoBugs
    Commented Sep 9, 2014 at 5:40
  • @NoBugs, you asked one question and got an answer, if this opens another question then the proper thing is to start a new question or discuss the answer in its comments. Anyway, the answer stand, the cookie structure (and IIUC hashing) was changed and everybody will have to login again after an upgrade to 4.0 no matter how the upgrade was done. Commented Sep 9, 2014 at 11:27

1 Answer 1


4.0 made a change to the structure of the authentication cookie and added a "token" feild to it. I assume that you were logged out because your older style cookie didn't match the new format.


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