Upgrade 1.3->1.6: Preview shows admin pane

[paux]

Hi,

Although this problem is in the FAQ http://www.s9y.org/11.html#A16, the FAQ doesn't mention how to actually solve it. In addition, everything had worked under s9y 1.3, but that problem now occurs with 1.6. The upgrade process as such seems to have been successful.

My system: Debian 'lenny' (still), Apache 2.2.9, PHP 5.2.6, MySQL 5.0.51a.

php5.ini:
session.use_cookies = 1
magic_quotes_* off

.htaccess:
php_value session.use_trans_sid 0
php_value register_globals off

I tried switching the theme, but that had no effect. It occurs in Chrome and Firefox. No errors in JS console. No errors in Apache logs.

Any hints?
Thanks!

[paux]

... aaaand the loser is:

The HTTP-Authentication (serendipity_event_httpauth) plugin!

I'd almost forgotten our special setup using HTTP authentication. Disabling "Grant REMOTE_USER Authentication" in that plugin re-enables the previews, while still maintaining the intended auth behaviour.