Courier is broken - it sends an EXISTS response during EXPUNGE 
responses even though the RFC explicitly says there is no need for 
this.  This has been worked around in horde/Imap_Client.

Changes have been made in Git for this ticket:

Bug #9915:  Work around broken IMAP clients that send EXISTS data in 
EXPUNGE response

  2 files changed, 55 insertions(+), 51 deletions(-)
http://git.horde.org/horde-git/-/commit/500d9d70740146f8603265ba5e16dd53779aa08c

It looks like there is an issue with calcualting the UID list after an 
EXPUNGE response.  Jan (and I) are probably not seeing this because 
the VANISHED response is being used instead.

This error by itself doesn't mean anything - it simply means that the 
AJAX response from the server was broken, most likely because the 
server fatally exited on an error.  So you must look at the Horde log 
to provide any useful information.

This is a duplicate of Bug #9845.

I'm facing the same problem.

When I am sending message, Nothing happens (only in error log new log) 
and I must press it again. Then it is sended.

PHP Fatal error:  Call to a member function get() on a non-object in 
/usr/share/php/Horde/Imap/Client/Socket.php on line 2946, referer: 
https://portal.tab-financial.cz/beta/imp/compose-dimp.php?type=reply_auto&folder=INBOX&uid=48811&ajaxui=1&uniq=1303154274052

I have the error , although i delete only a message.

Im using dovecot as imap server, and  postfix as mail software.

The message is deleted, but appears the notification...

When i using traditional mode, appears blank page when i delete a message.

This is my configuration in backends.php

$servers['imap'] = array(
     // ENABLED by default
     'disabled' => false,
     'name' => 'IMAP Server',
     'hostspec' => '10.72.3.29',
     'hordeauth' => false,
     'protocol' => 'imap',
     'port' => 143,
     // Plaintext logins are disabled by default on IMAP servers (see RFC 3501
     // [6.2.3])
     'secure' => 'notls',
     'maildomain' => '',
     // 'smtphost' => 'smtp.example.com',
     // 'smtpport' => 25,
     'cache' => false,
);



I' have a production server, with egroupware webmail Edition 1.2.9 and 
not have problems, only with new imp.

I've doubled checked, and this happens using traditional mode as well. 
This could be related to the IMAP server (I guess, I'm no expert).

I do this all the time without any issues.

Found !
Select all messages in a folder and delete them.

I see the 'Error when communicating with the server' as well. But it 
appears/happens really randomly and not very often. I haven't found a 
way to reproduce.

I use courier-imap 4.8.1
$_prefs['use_trash']['value'] = 1;
$_prefs['delhide']['value'] = 1;

For the following trace, I was using dynamic view, and deleting a few 
selected messages.

2011-04-18T09:13:40+02:00 ERR: HORDE [imp] IMAP error: Error in IMAP 
command received by server. [pid 15078 on line 219 of 
"/var/www/html/hordetest/libs/Horde/Imap/Client/Base.php"]

I'm facing the same problem.
Sometimes when deleting mail I do get the said error. IMAP log 
(dovecot here) shows: 2011-04-16 09:50:37 IMAP(theuser): Info: 
Connection closed bytes=101/996.
Horde didn't write any logs.

Check the Horde and/or IMAP logs.

For further debugging information, please read the 'AJAX 
Troubleshooting' section in imp/docs/INSTALL.

In IMP H4 (5.0) Final, i have a imap server configured in backends.php.

When i try delete one or severals messages, appears the notification:

"Error when communicating with the server"

In Kronolith this error it's solved in this ticket:
http://bugs.horde.org/ticket/9818

But i dont find any information about imp