After user authenticates they launch a published app or desktop, connecting window comes up but goes away after a few seconds. Delivery controller  Event ID 1101 Broker Service failed to broker a connection for user to resource. The citrix Broker Service cannot find any available virtual machines. 

1. Review Event logs on Delivery Controller and identify if error 1101 matches time of launch failure. 
2. Check details of event 1101 for information of resource impacted by issue. 
3. Open Studio > Select Machine Catalog impacted > View Machines
4. Review machines and identify VDA without any active session or with significantly less number of sessions than other VDAs. 
5. Attempt to RDP or start console session to machine identified in previous step. If it fails to establish a connection you have identified the machine preventing connections to the catalog. 
6.  Reboot the affected machine or place it in maintenance mode until it can be restarted.
7. Test and confirm users are now able to launch resources from Machine Catalog. 

Ideally, rebooting the machine that is in this state will resolve the problem in most cases, but it wont provide details on how the machine got into that state. Additional troubleshooting might be needed to determine cause of system hang. 

Problem Cause