VaRest error when starting dedicated server. Help!

We are trying to put the plugin “VaRest” from the github. (GitHub - ufna/VaRest: REST API plugin for Unreal Engine 4 - we love restfull backend and JSON communications!). when packing a project on win 64, we encounter the following error, when starting dedicated server. What should we do!?

Full rebuild project fixed error.

Was it a rebuild as “development editor” or “development server” in VS that did it?
Have same problem.

Did you find any solution?