Fatal Communication Error RRS feed

  • Question

  • Hello, everyone.

    I am fairly new to the world of SQL server, so I apologize for any newbie errors in my question. I am also not sure if this is an SQL, IIS, or Windows Server issue.

    The Environment:
    One physical server running Hyper-V
    Physical server is acting as domain controller, Hyper-v host and DNS server
    All servers are part of the same domain.
    Server version is 2012 R2 in all instances.
    SQL version is 2014 in all instances.
    .NET version is 4.5
    All software is fully updated.

    The Virtual Servers:
    SQL Server
    IIS Web Server
    Test Server with IIS and SQL

    The Problem:
    The IIS Web Server cannot connect to the SQL Server without the application pool crashing.
    The SQL Server logs show the login from the web server was successful.
    The web server’s event logs show a “fatal communication error with the Windows Process Activation service.”

    Other Facts:
    When the IIS server and SQL server are on the same “machine” (the test server mentioned above) there are no issues at all – everything runs normally.
    The website code is identical in both cases, as is the SQL configuration, including users and permissions.
    If the connection on the test (previously working) is changed to connect to the standalone SQL server, the problem triggers, the app pool crashes, and the error message in the event log is the same as in the standalone web server.
    For testing, the firewalls have been turned off on all servers and it makes no difference.
    Windows authentication and SQL authentication both have the same results.
    Using a standalone UDL file, a connection CAN be made to the SQL server from any other server, including the IIS Web Server where the app. pool crashes.

    I realize I am no providing actual examples, but based on the information above, I am hoping to get some direction on where to look for a problem. Most of the information I have found on the error deals with Sharepoint, which is not a variable in my case.

    Since the firewalls have been turned off, the problem only happens when attempting to connect to SQL from an outside server, and only happens through IIS, I am at a loss on what else to check.

    Thank you in advance for any relevant advice.

    • Moved by Kalman Toth Saturday, May 17, 2014 6:30 PM Not getting started
    Saturday, May 17, 2014 6:17 PM


  • Hello,

    By your description, it sounds like an issue with the IIS server. The fact you can connect to SQL Server using all methods except through IIS (where it crashes) means that connectivity is good and SQL Server isn't throwing any errors. My other thought is that there may be an issue with DNS and the way you have the virtual switches configured with the host.

    Unfortunately I don't know all that much about IIS or Hyper-V specific host configurations for something such as this. Someone here may be able to help you further, or it could be moved the IIS/Hyper-V specific forums. I'd be willing to continue to help out from the SQL Server side if that was to become the case.

    Sean Gallardy | Blog | Twitter

    Saturday, May 17, 2014 11:17 PM