Error starting simulation in mission planner

Hi.

Following this guide https://ardupilot.org/dev/docs/sitl-with-realflight.html

After selecting flightaxis, when I click on one of the aircraft type icons it says ‘downloading sitl software’ then I get this error:

Any ideas?

Ok, installing the MP beta fixed that…

Now sitl connects to realflight.

Next issue - when I try and load a param file in MP, I get this error:

Does anyone else see this error starting loading SITL params in Mission Planner?

param file from here: Param file from here: https://github.com/ArduPilot/SITL_Models/tree/master/RealFlight/Tridge/Planes/EFlightExtra300