Windows Update impacting licence validation?


Hi there,

We suspect that a Windows Update may have invalidated the machine fingerprint at one of our customers (we don’t have access to their logs now). We are using LexActivator in Python.
Are there any particular OS updates that can make licences become invalid?

Many thanks,
Tiago Costa


It might be related to Tiago’s question, so I’m adding it here:

We recently started to get error 64 (“machine fingerprint has changed since activation”) when using your library under Windows Subsystem for Linux (WSL) with Ubuntu 18.04 and 20.04.

Are you aware of this issue?



For licenses meant for apps running inside Docker or Linux WSL, you should set fingerprint matching strategy to exact.


First I should correct myself, the error code is LA_E_MACHINE_FINGERPRINT = 63 (not 64) and this error is returned from the LEXACTIVATOR_API int LA_CC ActivateLicense() function (I’m using the C library). This error code is not listed as one of the possible errors for this function on your header file.

Regarding your suggestion, how do I set the matching strategy to “exact”?


You are right ActivateLicense() is not supposed to return this error code. In fact the activation succeeds on server and appears in the list of activations.

This happens because Linux WSL gives almost no access to the host hardware details and fingerprint generated is so poor that it fails to pass the threshold score. We will fix this in the upcoming release so that it doesn’'t return 63 error code.

Fingerprint matching strategy is property of license. Edit the license and update this,


Hi Adnan,

I haven’t mentioned it but, actually, our customer is running our application inside Docker for Windows. And IsLicenseGenuine() has been returning OK until their last Windows update.

Regarding the solution you provided, can you explain why we should use “Exact” as the matching strategy when running inside Docker? Shouldn’t it make it even harder to get a fingerprint match than using “Fuzzy” or “Loose”?

Many thanks,
Tiago Costa


Hi Tiago,

Linux under WSL gives little access to the host hardware, which is not enough for the fuzzy to succeed. Hence exact is needed, so whatever was generated matches.


Hi Adnan, thanks for the explanation.