On attempting to launch any published application from a XenApp 6.0 server, the server reports that it is too busy to provide access to the selected resource.
The application event log contains the following entry:

The Citrix servers reported that they are too busy to provide access to the selected resource.
This message was reported from the XML Service at address <url> [com.citrix.xml.NFuseProtocol.RequestAddress]. [Unique Log ID: 2cbfa6dd]

• Ensure that you have added the correct license port (27000 by default) using the appropriate policy.

• Ensure that you have chosen the correct license server within the policy you are applying.

• Open the command prompt and run netstat -a on the Citrix member server to check whether 27000 (or your chosen port) has established a connection to Citrix license server.

• Consider the following fix or its currently available equivalent
  Hotfix XAE500R01W2K8X64014.
  During heavy server utilization, published applications can fail to launch. Instead, double-clicking an application icon causes the application to connect to the session but the session logs off immediately without launching the application. [From XAE500R01W2K8038][#249027]

• LogoffCheckerStartupDelay waits for the application to launch.
  For example:HKLM\SYSTEM\CurrentControlSet\Control\Citrix\wfshell\TWI
  LogoffCheckerStartupDelayInSeconds REG_SZ 600

Problem Cause

CTX129596 – Case Study: Applications Fail to Launch from One Domain in Multi-Domain XenApp 6 Farm

CTX134013– Case Study - Application Launch Fails with Event ID 30107

If the Citrix licensing server is at version 11.6.1 or later, you can specify the default ports using the post-installation configuration tool that launches automatically after installation and that can also be used to set the administrator password for the license server.

The tool can be launched using LsPostConfigtool.exe located in <systemroot>\Citrix\Licensing\LS\resource.