Multiplayer Server Connection Guide
Sponsored by Boston Virtual ATC

Problem: The "Trying to Connect" message remains on the screen, and I am never prompted to enter a session password.
Already Tried: I have already tried closing and restarting Flight Simulator. I am connected to the internet.

Most servers require you to have either the Acceleration Expansion Pack (payware) or the freeware FSX service packs installed. If you aren't running either of those updates, you probably won't be able to connect.

You can download Service Packs 1 and 2 for free. Both are required.

Service Pack 1 (install first)
Service Pack 2 (install after Service Pack 1)

If you are unsure whether you have the required updates installed, you can check the "Programs" list in Control Panel. Find "Microsoft Flight Simulator X" and look for the version number. The version numbers that are compatible with Acceleration/SP2 servers are v.10.0.61472.0 (SP2) and v.10.0.61637.0 (Acceleration). If you have any other version number, you will not be able to connect until you have installed the Service Packs from the URLs above. SP1 is a prerequisite for installing SP2.

Do you have Service Pack 2 or Acceleration installed?
Yes, and now connecting works. What's next?
Yes, but I am still unable to connect to the server
I am still unable to connect to the server but am receiving a different error