Recieving the error "The search request was unable to connect to the Search Service" when searching FAST Search from SharePoint, and common scenarios documented on TechNetdo not apply.
The TechNet article outlines the processes involved, and how any breakdown in communication may result in this error message. The processes may show up as "Dead' in the "nctrl status" output, or they may be running but unresponsive to requests. Both can indicate problems during initialization, and the following errors may be found in the logs of the three processes noted in section 2 of the TechNet article:
QRServer: Unrecognized attribute 'allowInsecureTransport'QRProxy: Could not load file or assembly 'Microsoft.IdentityModel ...'SAMWorker: Could not load type 'System.ServiceModel.Description.DispatcherSynchronizationBehavior'
All messages above indicate missing prerequisites that are required to be installed prior to starting FAST Search. They are normally installed by the FAST Search Prerequisite installer.
The individual packages can be installed directly, from the full list of downloads available here: