Dear Support, 

I have encountered problem during optimization process in CST Studio Suite  . Recently I converted my project files from CST 2024 to CST 2026 because of workstation migration and now I don't have access to older update version. Now often when I want to start calculation, error window appears that says:

It is happening mostly after few initial iterations of optimization. I don't know if this case is related to older version files or simply caused by modeling mistake. I hope that there is some easy explanation to this topic.

In attachment there are some logfiles from application crash.

Thank You!