Thank you for this bug report. To properly diagnose the problem, we
need a short but complete example script to be able to reproduce
this bug ourselves. 

A proper reproducing script starts with <?php and ends with ?>,
is max. 10-20 lines long and does not require any external 
resources such as databases, etc. If the script requires a 
database to demonstrate the issue, please make sure it creates 
all necessary tables, stored procedures etc.

Please avoid embedding huge scripts into the report.

Hi, thanks for interest :-) I am not a php programmer, so I don't know howto help any better, sorry. In the apache error log you can see this: /var/www/mail/modules/email/json.php on line 1310

so line 1310 is the last line of the json.php code, it's end like this: 

											
		}
	}
}catch(Exception $e)
{
	$response['feedback']=$e->getMessage();
	$response['success']=false;
}

if(defined('IMAP_CONNECTED'))
{
	$imap->close();
}

echo json_encode($response);

----------------------------------------------

line 1310 is this: echo json_encode($response);

I don't really know If this is help to you. Please let my know, I will contact programmer of this code. 

Thanks

Any strings passed to json_encode should be valid utf-8, the manual 
and error message make this clear.

OK, but there were no problems with json_encode (the same script) in the php version 5.2.5 and 5.2.6 .. So I don't understant what is wrong. 

Here you have whole script: 

http://www.gmork.cz/files/json.php.txt

It didn't work before, it just silently cut the string in half and you never noticed it.

See bug #43941

OK. Group-office is the php web aplication .. 
I am IT administrator of the linux systems, NOT a programmer (my fault) ... 

OK. If I have Groupoffice3 and php 5.2.6 on my server, I can read the email messages, no problem, no errors : 

http://www.gmork.cz/files/oldphpworks.png

OK. If I have updated php to recent version 5.2.8, some of messages which have been made in the php aplication Groupoffice3 CAN NOT be read: 

http://www.gmork.cz/files/test-again.png

So php developer says: "This is php bug" , so php developers says "This is not bug". OKI. Sorry I don't know what to think, because I am not goddam programmer at all ... :-(

I meant: So Groupoffice3 developer says: "This is php bug"

The fact that it worked before was the bug. It's now doing what it 
should have done in the first place.

OK. Thanks for all the replies and your time. Thanks very much.

Developer of the Groupoffice3 is saying: 

How can I work around then when a string contains invalid UTF-8 data? Is 
there a function to strip invalid chars?

I wrote an e-mail client and with 5.2.6 it worked fine and now my app 
stops working when there is an invalid char in an incomming e-mail. I 
have no control of that of course so I need a function to make the data 
clean

It really depends on what the context is and this sort of thing should be asked on the users list.