Mail not displaying in DIMP, was Re: Problems with Horde Interface after upgrade from 2.2.4 to 2.3.2

["Uwe Greßhake | dmmd GmbH & Co.KG"]

Am 28.06.2011 18:46, schrieb Christoph Wickert:
> On Tuesday 14 June 2011 11:28:43 Gavin McCullagh wrote:
>> Hi,
>>
>> On Tue, 14 Jun 2011, Christoph Wickert wrote:
>>>> How do I know which locales I need to install?  We're using British
>>>> English as the default language in Horde, or is this a question of
>>>> matching the locale of the email to display?
>>> AFAIK you need the language Horde is using in in both ISO* and UTF8. grep
>>> php- errors.log for "function.json-encode" and give us the relevant
>>> parts please.
>> These seem to have been the relevant messages:
>>
>> [13-Jun-2011 13:18:33] PHP Warning:  json_encode() [<a
>> href='function.json-encode'>function.json-encode</a>]: Invalid UTF-8
>> sequence in argument in /kolab/var/kolab/www/client/imp/lib/JSON.php on
>> line 86
> For the record: We are now tracking this issue at
> https://issues.kolab.org/issue4743
>
> Thanks to everybody who helped us to debug this so far.
>
> Regards,
> Christoph
>
>

This problem still exist in my fresh kolab installation of stable 
release 2.3.4.

Most mails are not displayed in dimp preview windows. Instead the error 
message
   "Your server is unable to render UTF-8 message. The preview won't 
work. Please contact your administrator."
is displayed. Not only the preview window is effected by this error:
Folder names, which contain non ASCII letters, are not displayed in the 
folder list in dimp, if they belong to the functional folders on top of 
the list (sent, trash, etc.). Non ASCII characters in From and Subject 
lines of new mails are wrongly converted and then badly displayed in 
other mail-clients.

In all cases the the horde json code is involved and the json_encode() 
error messages occur in the apache error log.

I installed all necessary locales and restarted apache, but it does not 
solve the problem.

Then I tried different client operating systems and different browsers 
and found out, that the error is independent of the client OS but it 
depends on the browser. So for me it seems to be a client server issue.
I compared the browsers and the conversation between the browsers and 
the server and examined, that the error occurs, if the browser does not 
sent the "Accept-Charset"-Header. If the "Accept-Charset"-Header is 
missing in the browser request, some code in the json libs in horde seem 
to be irritated and suffers from an undefined state.

My temporary workaround for affected firefox browsers is to install the 
"Modify Headers"-Add On from Gareth Hunt and manually add the missing 
header field.
I hope my analyse is helpful to solve this problem on server side.

Regards,
Uwe