Connection to contentdistributor FQDN:13391 could not be validated. Check your certificates and ssa configuration and make sure that instance of FAST Search Server backend is running.
Congratz! You are at the right place!
I encountered this issue when executing the SecureFASTSearchConnect.ps1.
I tried the following steps provided by Microsoft HERE and it still didn’t work!
If you have not read the KB, they basically tell you to replace the certificate, and reconfigure the FAST Search Connector to use port 13391.. well you have to at least ensure that the parameters keyed-in are correct. SSA name, Domain user account (which is used to run osearch14 services account, if your environment is 3 tier, please check the one that is running the SSA. Mine is at App Server).
Let’s assume that your search service is running on App server, you can double check the connection between the server running the OSEARCH14 service and FAST Search by running the following command at App server Powershell.
Ping-SPEnterpriseSearchContentService -HostName [FQDN]:13391 where [FQDN] is the fully qualified domain name of your FAST Search server
In my case, it is FALSE! all the time.
The cause of this connection failure is due to too many Trusted Root Certification Authorities in both my Apps Server and FAST Server.
Fire up “Run” and enter “mmc”,
File > Add/Remove Snap In (or Ctrl + M)
Select Certificate > Computer Account > Local Computer > Click Finish,
Click Ok again
Navigate to Certificate > Trusted Root Certification Authority > Certificates
[Refer here for detail steps]
Remove unnecessary certificates.
After trimming down the number of certificate. The connection now worked!! =)
Well, if you still having problem, my suggestion is to UNINSTALL AND REINSTALL your SharePoint and FAST Search all over again. Reason being is that the installation of SharePoint could be affected by the hardening which will not throw you any message or other software that imports unnecessary trusted root certification authorities to you server.