Can’t activate library/addin – shows XML error

If the Sigma application is blocking you from opening a library (e.g. a cost database) and showing you an XML error instead, the reason could be, that you are running on an older operating system.



The connection between Sigma and our licensing servers is encrypted using only reliable TLS or SSL protocols.

Currently supported protocols are TLS 1.2 and TLS 1.3.


Older operating systems only support TLS 1.1 which is no longer considered secure.

Check the following service for a list of operating systems that our license server supports:



The best solution is to upgrade your operating system to newest version to stay secure and connected.

The second best solution is to edit your path.ini file (found in your “Program Files (x86)\Codegroup\Sigma ..” directory) and edit all occurrences of “https” to “http”. Restart the Sigma application afterwards.