You have successfully implemented CRM servers and expect your Sandbox service to execute plugins in Isolation mode; however, they fail with an error:

The plug-in execution failed because no Sandbox Hosts are currently available. Please check that you have a Sandbox server configured and that it is running.

System.ServiceModel.EndpointNotFoundException: Microsoft Dynamics CRM has experienced an error. Reference number for administrators or support: #357E9BEE

Possible Cause:

1. CRM Sandbox service is not running

2. CRM Sandbox ports are unavailable

3. CRM Sandbox service is missing SPN's

4. CRM Sandbox is load balanced and Hosts cannot be reached

Potential Solution:

1. Ensure Sandbox services are running on each Full CRM 2011 Server.

2. Ensure you have TCP port 808 listed on your CRM Front end server IIS website.

   (Either on Default website or the Microsoft Dynamics Website)


Ref for more port information:

3. Check if you have the required SPN’s register against the Domain account used to run the Sandbox account.

   NOTE: It is best practice to have least privileged account run the Sandbox service.




    Ref CRM 2011 security consideration article:
    Ref- Easy generation of SPN’s for CRM 2011

4. If this is a Load Balanced Sandbox server then you may want to add the following registry key to the servers that run as Sandbox hosts.

     Key Name: sandboxforcemultiplebox
     Type: DWord (32Bit)
     Value: 1
     Location: HKLM\SOFTWARE\Microsoft\MSCRM

Warning Serious problems might occur if you modify the registry incorrectly by using Registry Editor or by using another method. These problems might require that you reinstall your operating system. Microsoft cannot guarantee that these problems can be solved. Modify the registry at your own risk.

NOTE: Step 4 is applicable only if you have multiple full CRM 2011 servers or multiple Sandbox hosts load balanced in an environment.

If the issue is not still not resolved please open a support case with Microsoft for additional support.

Kaustubh Giri

Microsoft Premier Field Engineer