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How to zero in on 502 gateway errors


We’re getting 502 bad gateway errors sometimes for some reports when validating or displaying parameter pages having parameters with several separate queries responsible for displaying value prompts.

Sometimes the reports run. Sometimes they don’t. Failure seems to happen after about 2 minutes (perhaps 2 minutes four seconds before the error shows up in the web browser).

For one of the reports, if I run the queries underlying them separately first (showing tabular data) and then run the report, the parameter page with the parameter values from those queries DOES complete within 2 minutes and the parameter page does render. I believe the queries in question are Oracle SQL Data queries (not Framework Manager modeled queries but pass through queries directly against Oracle).

Is there any likelihood that it relates to our content store and data source having been upgraded from Oracle 11gr2 to Oracle 12Cr2?

I would love to have a list of possible places to look for timeout settings and to know how to change the logging levels for which logs

We have Cognos 11.0.8 on Windows Server 2012 R2 Standard edition, with one dispatcher, a gateway running IS-API, SSL installed (except connecting to Oracle and the LDAP), Oracle 12cr2 for the content store, Oracle 12cr2 for a data source as well as a different 11G Oracle data source, IIS 8.5

The problem occurs in our development Cognos server but not our production Cognos server. The same setups exist for both except that production has some Windows updates yet to be applied and uses Oracle 11gr2 throughout instead of Oracle 12cr2. In production, no timeout seems to happen even after 3 or 4 minutes go by before reports validate or parameter pages display.


Thanks so much!

Mike Sullivan, North Shore Community College, 978 7262 4218 and msulliva@northshore.edu

Hi Mike,

What does the 502 error screen look like? Is it a page that looks like Cognos is presenting it or maybe an upstream web server/network device? I might suggest you check for configuration differences between your ISAPI IIS gateway on Development and Prod. There might be a request timeout or similar on IIS that is causing your request to timeout. You might find a clue in the IIS logs (I assume you have checked the Cognos logs already).

As you mentioned, if you can cause Cognos to cache some of the underlying data by using the “View Tabular Data” option and your request completes in under the approximate 2 minutes, the request succeeds.