Be Prepared: Known Issues for Upgrading to Windows Server 2008

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There are a few differences in MSMQ and IIS functionality between Windows Server 2003 (MSMQ v3.0) and Windows Server 2008 (MSMQ v4.0). This means that there are a few configuration changes you may have to make to your MSMQ system post-upgrade to make everything function the way it did on Windows Server 2003.

Issues with HTTP and transactional messages:

MSMQ’s transactional message support uses internal messages called “order ACKs” to coordinate between sender and receiver so that no user messages are lost. When transactional messages are sent via HTTP, the URLs used to send the order ACKs back to the sender sometimes contain the special character “+”. IIS 7 has a security feature in request filtering to disallow all double escaped characters, and this interferes with the return of order ACKs to the sender if the URL contains a “+”. This results in the transactional messages accumulating in the outgoing queue of the sender in those cases. In order to prevent this issue, which may arise any time transactional messages are sent via HTTP, you can disable the double escaped character filtering in IIS7 for MSMQ’s virtual directory. This can be done using the appcmd tool like so:

%windir%\system32\inetsrv\appcmd.exe set config "Default Web Site/msmq" -section: system.webServer/security/requestFiltering -allowDoubleEscaping:true -commitpath:apphost

To Keep Multicast working:

On Windows Server 2003, MSMQ’s multicast support was part of the MSMQ core optional component: if MSMQ was installed, support for multicast messages was also installed, as was the PGM Multicast transport which it depends on, and the firewall did not filter PGM traffic. In order to tighten security for users who aren’t using this feature of MSMQ, multicast support is now a separate optional component, and it is not installed by default during an upgrade. If you intend to use multicast messages after an upgrade, you must explicitly install it the same way you would install any other MSMQ subcomponent. You can either do this through the UI (in Server Manager), or on the command line via ServerManagerCmd. See my previous post on Unattended Installation for Windows Server 2008 for more information on unattended installations.

—Jolie Boushey