On checking the server log files.
Thread-74 LOGSV 2015 1
server.Audit.IPF StopService LogService
Failed Log Server socket error <parameters>
<item name="Port"><![CDATA[9362]]></item><item name="Error"><![CDATA[Connection reset]]></item></parameters>
Checked KB @ Cognos and at IBM Cognos website i could not find any documents :-X
The reports were upgraded from version 8.3 to 8.4, some of the reports failed to run.
The reports were using SQL Query items (External Data) to retrieve data directly from another database
later the results from this query were joined to the Query Items (From Package)
the SQL Syntax property was set to
Native this worked fine in BI Version 8.3
but on 8.4 something got changed!
Solution:
Changing the SQL Syntax property to Pass-Through fixed the error and the reports work fine.
Hope no more surprises from Version 8.4