Error: Object reference not set to an instance of an object at CodemeterApp.Units.CodemeterApp.AccessCodeMeterLicence(…)

When starting Diamonds, you get the error:

Followed by

Diamonds opens after that, but an error appears whenever you try to do something, like drawing a line, opening the section/material libary, running the structure generator .

Solution

This issue is caused by a big difference in Codemeter versions between the users computer and the one on the license server (for example: v7.51 versus v6.70).

• Reinstall Codemeter Control Center on the client’s computer.
  Test if the issue is solved. If not continue with the steps below.
• Reinstall Codemeter Control Center on the license server computer.