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Fetching a license results in FLEXlm -15 or -97 error



Attempts to fetch a license for an IBM Rational product fails the first time resulting in the error FLEXlm -15 or -97.


This is seen when the first contact (or even subsequent contacts) made by the client machine fails to retrieve a license throwing FLEXlm -15 or -97 error intermittently or consistently.

The license server is working fine and serving the licenses, and subsequent launches of the product does not seem to throw any errors and able to pick up a license.

It is also seen to have shown intermittent license retrieval failure.


The underlying cause lies in the DNS resolution time lag, or in broader terms the time taken for the request to reach the license server.

Resolving The Problem

You need to set a environment variable FLEXLM_TIMEOUT in order to prolong the time out value on client side.

This environment variable can be set through the following steps:


This solution contains information about modifying the system registry. Before making any modifications to the Microsoft Registry Editor, it is strongly recommended that you make a backup of the existing registry. For more information describing how to back up the registry, refer to Microsoft Knowledge Base article 256986

  1. Open the Registry editor (click Start > Run > type regedit)

  2. Navigate to the following registry key:


  3. Create a new key

    Type = String Value
    Value = 20000000

    Note: This value is the default value if this variable is not explicitly specified as 100000 microseconds

  4. Close out of registry

  5. Launch the Product

[{"Product":{"code":"SSTMW6","label":"Rational License Key Server"},"Business Unit":{"code":"BU053","label":"Cloud & Data Platform"},"Component":"FLEXlm","Platform":[{"code":"PF033","label":"Windows"}],"Version":"7.0;7.0.1;7.1;7.1.1;8.1.1","Edition":"","Line of Business":{"code":"LOB45","label":"Automation"}}]

Document Information

Modified date:
16 June 2018