We're unable to open attachments through OWA when connected to a particular CAS server.  If we open OWA by specifying the problem server directly, when we click on an attachment nothing happens; the browser (IE, FireFox, Chrome) just spins and spins.  We're testing with a .txt file, but the problem seems to be affecting all file types.  OWA on our other CAS server prompts to download the attachment immediately.

We've compared the OWA virtual directory settings on both the working and non-working CAS server but did not spot any differences.  Also, We've also tried deleting and recreating the OWA website with "Remove-OwaVirtualDirectory" and "New-OwaVirtualDirectory" without having corrected the issue.  We've restart IIS with iisreset, and, reboot the trouble CAS server without resolution.

We're not sure where to look to debug this.  We've checked the IIS web log and did not spot any issues.  Forums don't seems to be turning up much for this problem either.

Background: Running Exchange 2013 cu8 across two CAS/Mailbox servers.  A round-robin DNS record shoots traffic to one of our two CAS servers randomly.  End-users are randomly unable to open attachments, depending on which CAS server they are directed to.

Please let me know if you need any further information, or, have any ideas on what to check to resolve the issue.  Thanks in advance.

Hi,

Can users open attachment from Outlook when connecting to the trouble CAS server?

Are there any errors when user open attachment from OWA?

Please run UpdateCAS.PS1 to check this issue, open Exchange Management Shell as administrator:

1. Navigate to Bin Folder for Exchange 2013 server and run it as below
2. .\UpdateCAS.PS1

Also please compare the following settings between that two CAS server.

Open IIS Manager, double click on Request filtering, and 'edit feature settings'

Best Regards.

Hi,

Please compare this file contents between CAS servers.

%ExchangeInstallPath%FrontEnd\HttpProxy\owa\web.config

Configure client-specific message size limits:

https://technet.microsoft.com/en-us/library/hh529949%28v=exchg.150%29.aspx?f=255&MSPPError=-2147217396

Thank you for the reply, Lynn.

We've successfully run "UpdateCAS.PS1" followed by an iisreset but are still experiencing the same issue; clicking on an attachment through OWA on a specific CAS server results in no response.

Also, we've compared the feature settings for the two CAS servers as requested and, again, have not spotted a difference.

Thanks for the suggestions.  We're still trying to find an error message help us locate what might be causing the issue.  Please let me know if you have any further advice.

Thanks for replying, Satyajit.

We ran a diff between the "web.config" files on both CAS servers and the only difference was the "X-FEServer" value, as expected:

<add name="X-FEServer" value="EXCHANGE1" />

...versus...

<add name="X-FEServer" value="EXCHANGE2" />

Thank you for taking the time to reply and please let me know if you have any further suggestions.

Hi,

Check the result for this:

Get-OwaVirtualDirectory | fl Server,*SaveAttach*

Server:                               EXCH1
ForceSaveAttachmentFilteringEnabled : False


Server:                               EXCH2
ForceSaveAttachmentFilteringEnabled : False

Compare the associated param