User Culture cannot be set when Exchange 2010 SP1 CAS proxies to an older server version


When you connect to an Exchange Server 2010 Client Access Server running Exchange Server 2010 Service Pack 1, and you must proxy to an internal Client Access Server running the original Release to Manufacturing (RTM) version of Exchange Server 2010, you receive the following error:

HTTP 400 - Bad Request will occur in Internet Explorer. IIS logs show:

2010-11-15 16:40:38 POST /owa/ev.owa oeh=1&ns=HttpProxy&ev=LanguagePost&v= 443 contoso\user2 Mozilla/4.0+(compatible;+MSIE+6.0;+Windows+NT+5.2;+SV1;+.NET+CLR+1.1.4322) 400 0 0 31


This only occurs for first-time OWA users in the Exchange 2010 environment.  These users are not prompted to set the User Culture or Time Zone.  


Microsoft is investigating this issue.


To work around this problem, user one of the following methods:

Method 1

  1. On an Exchange Server 2010 Service Pack 1 computer, launch the Exchange Management Shell with the appropriate Administrative permissions.
  2. Type the following cmdlet and press enter:
    Set-MailboxRegionalConfiguration -Identity <Username> -Language en-us -TimeZone  Central Standard Time

    The example cmdlet above specifies the Language as US English, and the Time Zone to US Central Standard Time.  Change the language or time zone as needed for your user.

For more information on the cmdlet, see the following topic from Microsoft TechNet online:


Method 2

Update the target Client Access Servers in the organization to use Exchange Server 2010 Service Pack 1.

More Information

Per the Cause section, Microsoft is investigating this issue and will update this article with additional information in the future.

For more information on this topic, see:

Understanding Proxying and Redirection