In NetSim v11.1 when attempting to open a saved experiment or creating a new network scenario, a blank error message window as shown below may appear as shown below:
Similarly, an error message (could not find javafx.fxml Load Exception) window indicating that some of the files are missing while attempting to load NetSim UI components may appear as shown below:
The possible reasons for this error include
1. Unavailability of resources (Memory / Disk / CPU) in the PC / Laptop / VM.
2. Scanning of certain NetSim jars / binaries by Anti-virus software / Windows security which slows down the internal thread operations.
Resolution:
1. Shut down resource consuming applications such as Visual Studio, Chrome etc
2. Exceptions needs to be added for NetSim in the Antivirus and Windows Security tools to avoid the error.
Following articles explain the steps involved in adding exceptions for NetSim in some of the Antivirus and security tools:
Adding exceptions for NetSim exe's in Kaspersky Antivirus
How to add exceptions for NetSim in Trend Micro Antivirus?
3. The PC / Laptop / VM running may have very low RAM. The Min RAM required is 4GB.