Error 6: Activation Library Initialization error #6. Please, contact software vendor to resolve the problem.

License library initialization failed with error: Activation Library Initialization error #6. Please, contact software vendor to resolve the problem.
Error 6: Activation Library Initialization error #6. Please, contact software vendor to resolve the problem.

Tekla Structures License Server installation directory contains DLLs that are from the previous Tekla Structures License Server version. To resolve the issue you need to:

1. Close Tekla Structures License Administration Tool and stop the Tekla Structures License Server in LMTOOLS.
2. Uninstall all existing Tekla Structures License Server installations.
3. If the Tekla Structures License Server installation directory contains any DLL files remove them manually.
4. Now you can install Tekla Structures License Server to the same directory where the uninstalled version was.

Note: deactivation is not needed. Licenses are kept safe in Flexera Software specific location that is outside Tekla Structures License Server installation directory.