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Siteminder ERP Agent v5.6 SessionLinker Error - "[ERROR] AE failed to load library 'NPSSessionLinker'. System error: Unknown Error."


Article ID: 53833


Updated On:


CA Single Sign On Secure Proxy Server (SiteMinder) CA Single Sign On SOA Security Manager (SiteMinder) CA Single Sign-On



When initially configuring the SessionLinker component of the ERP Agent on the Policy Server, you may see the following error message in the Policy Server "smps.log" error log:

"[ERROR] AE failed to load library 'NPSSessionLinker'. System error: Unknown Error."


  • Check your SessionLinker Active Response to ensure "npssessionlinker" is entirely lowercase. This is most often the cause of the failure, as the Policy Server will construct the library name from this string directly. For instance, in Windows it will construct the following:

    "<library-name>" + ".dll"

    while in unix it will construct:

    "lib" + <library-name> + ".so" (or other appropriate extension)

    Thus, if you do not type the library name in the proper case, while it may work in Windows, it will not find the library in a unix environment.

    Secondary possibilities for this error follow:

  • Confirm that the proper sessionlinker library exists within the Policy Server 'bin' directory (e.g. "" for unix, or "npssessionlinker.dll" for windows, etc.).

  • The SessionLinker (Active Response) library has executable permissions.

  • If in a unix environment, the location of the sessionLinker library is in the LD_LIBRARY_PATH environment variable

  • Ensure that the SessionLinker library is not corrupt (compare to a known-working library on another server, or a fresh installation of the Policy Server-side ERP Agent components).

  • Check the version of SessionLinker library using the NPSVersion tool. Ensure that the version matches the ERP Agent version you are attempting to install.


Component: SMSSW