[Tickets #6959] error 500 in imp/redirect on failed login

[bugs at horde.org]

DO NOT REPLY TO THIS MESSAGE. THIS EMAIL ADDRESS IS NOT MONITORED.

Ticket URL: http://bugs.horde.org/ticket/6959
------------------------------------------------------------------------------
  Ticket             | 6959
  Created By         | support at pwv-shops.de
  Summary            | error 500 in imp/redirect on failed login
  Queue              | IMP
  Version            | 4.2
  Type               | Bug
  State              | Unconfirmed
  Priority           | 2. Medium
  Milestone          |
  Patch              |
  Owners             |
------------------------------------------------------------------------------


support at pwv-shops.de (2008-06-20 03:06) wrote:

I know this should be a problem with php or apache2, but I don't know  
what to do anymore. I'm using Horde Groupware Webmail Edition on  
Apache 2.2 with PHP5 (fast-cgi). Auth works over IMP (Cyrus 2.2 IMAP).  
All works fine, I can login, I can read mails, can create users and so  
on. I can do nearly everything in Horde when logged in. The problem  
is, when I log in with wrong username or password. The application  
works for some seconds and I get an error 500 and Apache error log says:

[Fri Jun 20 08:41:41 2008] [error] [client 85.232.9.189] Premature end  
of script headers: redirect.php, referer: https://xxx/imp/redirect.php
[Fri Jun 20 08:41:42 2008] [notice] mod_fcgid: process 4226 going  
graceful shutdown, sending SIGTERM
[Fri Jun 20 08:41:48 2008] [warn] mod_fcgid: process 4226 graceful  
shutdown timeouted, sending SIGKILL
[Fri Jun 20 08:41:54 2008] [notice] mod_fcgid: process  
/var/www/horde/imp/login.php(4226) exit(communication error), get stop  
signal 9

No other log provides more information. What can I do?
When calling redirect.php direct in browser, I get redirected to login  
page. What's wrong? I don't believe in wrong configuration of the  
webserver (because all is fine when I'm correctly logged in).