I'm having SIMBRIEF ERROR EXCEPTION1 = HTTP RESPONSE CODE SAID ERROR with version 2.7.3.
So no, you don't have the same error of the OP (SIMBRIEF ERROR EXCEPTION1 = %D FORMAT: A NUMBER IS REQUIRED, NOT UNICODE"), which as I've said was fixed in 2.5.0.
I can only confirm there are no issues whatsoever with GSX and Simbrief now, see the attached screenshot I just made now as a test so, the problem is on your side so, just be sure of the following:
- Your Simbrief Alias is correct. This is NOT your Pilot ID ( numeric ), it's the name/alias. The Pilot ID won't work.
- Your flightplan hasn't expired. The last generated flight expires after some time, then is not accessible anymore, until you take it from the saved flight plans and generate it again.
- Your firewall or antivirus is not blocking outside connections made by GSX ( the Couatl_MSFS.exe engine, most likely ), which is the most likely cause if you are 100% sure of the previous two points.