“RPC Server is unavailable” error when requesting a certificate

by Shijaz Abdulla on 06.02.2010 at 00:29

While trying to request a certificate using the Certificates MMC snap-in on a computer running ISA Server, Threat Management Gateway (TMG) or Unified Access Gateway (UAG), you may encounter the following error:

“The RPC Server is unavailable”


This may be caused due to the RPC Filter in ISA Server/TMG. The RPC filter ensures security by monitoring RPC traffic flowing through the firewall. DCOM traffic is also dropped by this filter. However, DCOM is required to request a certificate.

To workaround this problem, disable strict RPC compliance setting on ISA Server/TMG. Here’s how to do it:

  • Right click on Firewall Policy and choose Edit System Policy .
  • Under Authentication, select Active Directory configuration group
  • Uncheck the Enforce Strict RPC Compliance option.


  • Click OK and apply your changes.

Of course, you will also need to create a firewall policy rule to allow all traffic from Localhost to Internal. Once you have requested the certificate you can revert these changes.


You can now request certificates from your ISA Server/TMG computer!

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13 Responses to “RPC Server is unavailable” error when requesting a certificate

  1. New blog post: “RPC Server is unavailable” error when requesting a certificate on #ISAServer or #TMG http://tinyurl.com/ydy268a

  2. Peter says:


    I was looking a long time for this solutions !!!

  3. Mohammed Ziad says:

    Many Thanks dude , this resolved my issue !

  4. Robbie says:

    What about trying to access the TMG server for remote monitoring using DCOM over RPC. When I run wbemtest from the monitoring server and try to connect to the TMG server to test I get The RPC server is unavailable.

  5. Adrian says:

    Hi Shijaz,

    Are you local here in Qatar?
    possible you can send me an email with your contact details?
    I am here in Qatar too, would be nice to meet you….

  6. Thanks man! This helped me today, I first tried using RPC(All Interfaces) as the protocol for the rule that allowed communication from localhost to internal. This did not work, I changed it to “All Outbound Traffic” and it started working!

    Awesome, cheers.

  7. Paul says:

    Hi ,i am getting same error but in diff situation,i have configured ISA 2004 on server 2003, but when i am trying to access my domain through policy ,it showing that RPC server is not available2,pls any one help me

  8. Nawaz says:

    i have two tmg standalone servers, between them i want to create NLB. but while trying to add the second node to NLB i am getting error “the rpc server is unavailable on the specified computer” in NLB console and in event viewer system logs this error “dcom was unable to communicate with the computer ip using any of the configured protocols”
    i have also created the access rule but still no luck.

    can you help

  9. Pingback: How To Fix Error 26004 Rpc Server Unavailable Errors - Windows Vista, Windows 7 & 8

  10. Pingback: Ccertrequest Error

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