In windows Plesk webmail horde when trying to  logout it would show an error like as below and won’t let you logout as well.

The error is
“This request cannot be completed because the link you followed or the form you submitted was only valid for minutes. Please try again now.”

The possible solution for this issue is,

Edit C:\inetpub\vhosts\webmail\horde\lib\horde.php (Drive Letter will depend on where you installed Webmail/Plesk and configured IIS to load virtual hosts from)

And search for section ” SESSION[‘horde_form_secrets’ ” in the Horde.php and instead of

if ($_SESSION[‘horde_form_secrets’][$token] + $GLOBALS[‘conf’][‘urls’][‘token_lifetime’] * 60 < time()) {
return PEAR::raiseError(sprintf(_(“This request cannot be completed because the link you followed or the form you submitted was only valid for %s minutes”), $GLOBALS[‘conf’][‘urls’][‘token_lifetime’]));
}

it should be

if (($_SESSION[‘horde_form_secrets’][$token] + $GLOBALS[‘conf’][‘urls’][‘token_lifetime’]) * 60 < time()) {
return PEAR::raiseError(sprintf(_(“This request cannot be completed because the link you followed or the form you submitted was only valid for %s minutes”), $GLOBALS[‘conf’][‘urls’][‘token_lifetime’]));
}

Note the extra braces in red + bold