Troubleshooting
Problem
Running reports to Excel introduces an additional one minute delay for some users. This will typically manifest with Excel 2003 or newer, when reports are opened from Internet Explorer. The issue does not appear to occur with other web browsers. The Excel reports do open after the one minute delay.
Symptom
Does not occur in browsers other than Internet Explorer.
Web server logging shows an HTTP/405 response returned to the client.
Cause
The Cognos Dispatcher returns an HTTP/405 Method Not Allowed to an additional request sent from Excel.
This additional request generated directly from Excel is a feature identified by Microsoft at: http://support.microsoft.com/kb/838028 under the heading Understanding Microsoft Office Protocol Discovery.
Environment
Any (Apache, IBM HTTP Server, Microsoft IIS, and ServletGateway deployments are affected)
Diagnosing The Problem
Fiddler traces run on the client systems affected will show Excel making an additional HTTP/HEAD request which takes 1 minute before failing with an HTTP/405 Method Not Allowed response.
Resolving The Problem
Currently two workarounds (one for Apache/IBM HTTP Server, one for Microsoft IIS) have been determined to alleviate the issue.
Steps for Apache / IBM HTTP Server
Utilizing the mod_rewrite functionality, header requests on the web server may be blocked before any processing by the Cognos Dispatcher takes place. This will remove the delay in opening of the files.
To configure this, first uncomment the mod_rewrite line in the httpd.conf file:
- LoadModule rewrite_module modules/mod_rewrite.so
Then add the following to the httpd.conf configuration, above the ScriptAlias definition:
- <Location /ibmcognos/cgi-bin/cognos.cgi>
RewriteEngine On
RewriteCond %{REQUEST_METHOD} ^HEAD
RewriteRule .* - [F]
Options ExecCGI FollowSymLinks
</Location>
In the event that the Apache or IBM HTTP Server are configured to utilize the Cognos module, update the existing Location directive as follows:
- <Location /ibmcognos/cgi-bin/mod2_2_cognos.so>
RewriteEngine On
RewriteCond %{REQUEST_METHOD} ^HEAD
RewriteRule .* - [F]
SetHandler cognos-handler
Options FollowSymLinks
</Location>
Once these updates are complete, save the httpd.conf and restart Apache for this to take effect.
Steps for Microsoft IIS
Similar to above, Microsoft has documented steps for performing Request Filtering on specific HTTP verbs in IIS. To work around this issue, HTTP/HEAD request filtering must be configured in order to block these requests at the web server, before they reach the Cognos Dispatcher, which will remove the delay.
In the steps below, if the Request Filtering option is not present, the installation of an additional Administration Pack option for IIS is required. This is available at: http://www.iis.net/expand/AdministrationPack
These are the steps to enable this functionality:
- Click Start, select Administrative Tools, and click Internet Information Service (IIS) Manager.
- Expand the web site hosting your Cognos installation (usually Default Website), then your ibmcognos virtual directory, and select the cgi-bin entry.
- In the Home section, open the Request Filtering option.
- Select the HTTP Verbs tab, and then click the Deny Verb action on the right-hand Actions panel.
- In the dialog box, enter: HEAD
- Select OK.
Related Information
Was this topic helpful?
Document Information
Modified date:
15 June 2018
UID
swg21570035