Dynamics CRM in the Field

Information from the Microsoft Dynamics CRM PFE team working in the field

The plug-in execution failed because no Sandbox Hosts are currently available.

The plug-in execution failed because no Sandbox Hosts are currently available.

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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 Causes:

  • CRM Sandbox service is not running
  • CRM Sandbox ports are unavailable on the sandbox server
  • CRM Sandbox service is missing SPN's
  • CRM Sandbox is remote and the CRM Services cannot be reached

Potential Solutions:

  • Ensure Sandbox services are running on each Full CRM 2011 Server.
    NOTE: Sandbox services are not required to be on a CRM Full serve role, but by using this option the local CRM platform and Async service will use the local sandbox instead of using one over the network.
  • If you are hosting the sandbox service along with one of the IIS dependent server roles , ensure you have TCP port 808 listed within IIS manager bindings for net.tcp.

    Ref- For more port information: http://technet.microsoft.com/en-us/library/hh699823.aspx
  • 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. 
  • Example: 
    Ref- CRM 2011 security consideration article: http://technet.microsoft.com/en-us/library/hh699825 
    Ref- Easy generation of SPN’s for CRM 2011 

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

Kaustubh Giri

Microsoft Premier Field Engineer

  • We are experiencing this error for online.

    Can you please throw some light for the error

    "The plug-in execution failed because no Sandbox Hosts are currently available"

    to be thrown in crm online environment?

  • Hi Farina, sorry it's taken a while to get back to your comment.  If you're seeing this for online please open a support ticket and ask them to investigate so they can narrow down why this is happening - thanks!


  • We have asynchronous plugins configured in CRM with 3 servers running on Load Balancer. One of the servers is throwing the below error while processing requests by executing asynchronous plugins (as it does not have full installation).

    System.ServiceModel.EndpointNotFoundException: Could not connect to net.tcp://<server>CrmSandboxHost. The connection attempt lasted for a time span of 00:00:01.0156250. TCP error code 10061: No connection could be made because the target machine actively refused it <ip>:808.

    All the posts I have seen and the replies from different users is that, to have the firewall port that the Sandbox uses (port 808), open.

    I wanted to know against what program (EXE) should TCP connections be opened on port 808.

    Or please suggest an alternative solution.

  • Rupak,

    Is this 2013? Also, are your sandbox servers are separate from the front end servers? Is this causing errors in CRM or are these just in the event log?  



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