Article ID: 114451, created on Jul 27, 2012, last review on Aug 12, 2014

  • Applies to:
  • Plesk 11.x for Linux
  • Plesk 10.x for Linux
  • Plesk 9.x for Linux/Unix
  • Plesk 8.x for Linux/Unix


Note: The article applies only to Debian OS-es.

There are more than 600 domains on the server. When I try to log in to Horde, it says that the password is incorrect, even though I am entering the correct credentials.

The Horde test page ( reports an error when trying to authenticate:

Unable to create selectable TCP socket (3531 >= 1024)

Also, an Apache restart may fail with this error in logs:

[Thu Jul 26 23:53:42 2012] [notice] caught SIGTERM, shutting down
(24)Too many open files: apache2: could not open error log file /var/www/vhosts/
Unable to open logs


The issue is caused by a bug in the uw-imap package of Debian systems:

BUG #478193: php5-imap file open error >1024

The PHP imap_open function has a check that will not allow you to create a connection if there are more than 1024 files opened by Apache.


To resolve it, enable piped logging for Apache, as is described in this KB article:

2066 How do I enable Piped Logs for Apache Web Server?

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