I am getting a FlashDevelop error when I type "." after a variable. When the tooltip appears, I see "Fatal error: exception Failure("Couldn't connect on 127.0.0.1:6000")

This started happening when I uninstalled FlashDevelop 4.0.3 and installed 4.0.1. I installed fresh, along with all SDKs. I also rebooted the machine.

Net 2.0, Windows XP SP2. This is a Haxe/NME project.

FD can't connect to Haxe compiler for autocompletion.Try changing CompletionServer to Compiler.

This can probably be fixed by installing the latest version of FD. What was your reason to downgrade?

I don't see that particular setting. All I see is "Disable Compiler-based Completion" which was already set to false. I'm using FD 4.0.1

I downgraded because I couldn't get the profiler to connect to my SWF in 4.0.2 or 4.0.3. This is a Haxe NME project. You should be able to replicate the problem by creating a fresh NME project and testing the project with the profiler started.

I just tested - and the profiler works for NME projects.
For me this is even more surprising, since I couldn't get it to work for AS3 projects for months.

Try clean install for FD 4.0.3.