The latest update for SBS 2011 Best Practice Analyzer incorrectly advises setting the OWA website's web.config maxRequestLength to the number of bytes set for the Exchange MaxSendSize. Following this advice broke OWA- I could see messages, but trying to delete a message failed with a cryptic "Error has occurred" message. Checking the IIS documentation shows that maxRequestLength is kilobytes, not bytes, and the existing limit is already very large. I don't think it needs changing. There is however an additional setting for maxAllowedContentLength which is in bytes. I raised that setting to the MaxSendSize without getting any errors in OWA.
I recommend ignoring this warning, or applying the setting to maxAllowedContentLength instead of maxRequestLength.
---BPA Warning---
Issue: The Internet Information Services (IIS) virtual directory for EWS has a maxRequestLength value that does not match the get-transportconfig MaxSendSize value.
Impact: Setting an incorrect or inconsistent MaxRequestLength value can cause email delivery failures or an HTTP 404 error in OWA. Additionally, users may not be able to use OWA to send as large a message as they can send by using the Outlook client itself.
Resolution:
1. Find the Web.config file on the Client Access server. The default location is C:\Program Files\Microsoft\Exchange Server\V14\ClientAccess\exchweb\ews.
2. Make a backup copy of the web.config file.
3. Start the Exchange Management Shell and use powershell "get-transportconfig | ft MaxSendSize" to get the global max Send size, for example, 20M.
4. Find the maxRequestLength value, and change it to the value that you want. The value is in Bytes. The maxRequestLength value in the Web.config file: <httpRuntime maxRequestLength="2097151" />. Make this value match the one from get-transportconfig
command line.
5. Save and close the web.conifg file.
Paul