KB30457: "QueryEngine encountered error: Unknown failed. Unable to connect. Error type: System call error. Error communicating with connection process. Intelligence Server single allocation limit exceeded..."

SYMPTOM
When running a report or document in Strategy Intelligence Server 9.x - 10.x, the following error occurs:
 

QueryEngine encountered error: Unknown failed. Unable to connect. Error type: System call error. Error communicating with connection process. Intelligence Server single allocation limit exceeded. Please check report size and/or incremental fetch settings..

 
CAUSE
The error messages shown above signify that the job errored out because it exceeded an Intelligence Server setting for memory governing. 
 
ACTION
One possible solution for this issue is to redesign the report to reduce the result set returned so that the size of the report stays within the limits imposed by the Strategy Intelligence Server.  The limiting setting in this situation is the "Maximum single allocation size" which is a megabyte limit of report size.
 
The other possible resolution to this issue is to Increase the Maximum single allocation size located in Configure Strategy Intelligence Server -> Governing -> Memory Settings: The maximum single allocation size (MBytes) is a configurable parameter. Any single request from an internal component that exceeds this value is denied and the users shall receive a message as show above (though the same component may make multiple requests individually smaller than this limit but cumulatively larger).