Project set up like the web page: https://www.visualmicro.com/page/Teensy-GDBDebugging.aspx

Worked fine for a while.  Later, I started to get the can't start up debugging
message:

Unable to start debugging. Unexpected GDB output from command "-exec-run". Don't know how to run.  Try "help target".

The "dual serial" comm ports are no longer listed in the drop down on the IDE.
They are also no longer listed on Win 10 Device Manager.

Can't reliably bring them back.  Any ideas?

Sent by email is a log for re-build after a "clean"

As I said before those two ports have disappeared from the IDE.  They used to be there and now they are not.  See the images.  Attach to process does the same thing

Recycled power several times and it made no difference.

Swapped cables and the first time I inserted it, Windows reported a com5 created (connected to a T3.6 not a T4.1).  Opened Visual S. for that T3.6 box and the com5 showed there.  When I tried to compile/upload a T3.6 program it would not load and the com5 disappeared.  Can not make it or any other com ports come back.

I think there is more to it than that.

Many hours of experimenting later here is what I know.

The serial debug port did not "disappear" from Windows Device Manager.  Instead it disconnected whenever upload was triggered in VS.  I learned about "hidden devices".  It was there but disconnected.  Switching to Arduino !.8.19, compile/upload, then press the button on the Teensy reconnected the port.  Then all was well while you compile and upload from Arduino.  Switch back to VS IDE and you could watch the serial data from the Teensy program on the reconnected VS port.  As soon as you compile and upload on VS, the port disconnected.  Going back to Arduino would re-connect it.  From VS I could not load a one line program into the T3.6 or the T4.1.  The serial port always disconnected.

Now, the very bizarre.  I was annoyed during all this that VMicro stuck a message about "Converting solution to latest format".  I finally did that and then VS could compile and upload the program.  That message claimed that this only affected intellisense.  Now, if I watch the VS upload, Device Manager shows the port disconnected temporarily, but then it comes back a few seconds later and my program works normally.  The other oddity is that after the "Converting solution" the Solutions Platform no longer says x86.  It now says ARM.  This makes sense, but did that conversion really only affect intellisense.

There was one more message that appears in the VS output log that says

Teensy should be selected from "teensy ports" rather than "Serial ports" in Arduino's Tools > Port menu.

Don't understand why VS would put that one out.  Over in the Arduino ide I had selected Teensy not Serial.

I will now try to do the debugging once again.  I'm pretty convinced this problem was never Windows, because Arduino IDE always behaved normally and reconnected the port, then uploaded automatically thereafter. The problem seemed only within VS.

Well now I'm back where I was with the original post.  Can compile and load with Arduino and everything is good.  But I tried one time to use GDBStub debugging like before and now every time I upload, the port disconnects.  Happens for Release and Debug.  Now I can not use VS at all.

Is this data from the loader any help?

If I understand correct, Arduino and Visual Micro work the same without GDBStub.

GDBStub and teensy 4x is working for us on multiple boards. Visual Micro doesn't have to do anything special except lauch the vs debugger.

It is important to be clear about which dual serial ports you have configured. One using Serial and one using SerialUSB1?

The teensy loader doesn't show much. The information shown in the yellow box above, after clicking Debug>Start, will show us your config. 

Is "tools>options>visual micro>communications>network discovery" enabled?

However the next line is:

Port Discovery Error    The given key was not present in the dictionary.

First of all.  I am not doing any debug right now.  Just trying to get Release code to build/load/run.  The entire program is this:

void setup() {
  Serial.println("\nStartup");
}

// the loop function runs over and over again until power down or reset
void loop() {
  Serial.println("\nNext");
  delay(1000);
}


In your last response:

First:  Agree those last three lines behave like you said.

Second:  Agree that the Arduino build disconnects and then re-connects with the above code and all other code tried.  The VM build is release not debug, so there are no additional ports.  The VM build does not re-connect after upload.  The output window says the upload completed but the port remains disconnected.  The only way I can find to re-connect the port is to use the Arduino IDE (1.8.19).

Third:  I don't understand.  Since I'm trying to run Release mode now, why would I select dual serial.  Before, when I was trying to run Debug mode, I did select 
Dual Serial.  The very first time I did that, the system worked exactly the way your tutorial says.  Two new ports were presented, the lower number was selected for serial output and the higher was selected for debug.  I built, it uploaded, connected and I could use the debugger commands.  About the third time I changed the source code, the IDE stopped connecting to the debugger.  I started getting the message in the Original Post.  I have only seen the two additional ports presented once more when I created a new project with only a few lines of code in it (the above code plus the required references to GDB).  Now it won't even do that, so I abandoned GDB altogether, took out the references to GDB and tried just to build the simplest project with Release properties.  So hear I am,  VM can not load the above program at all.

Fourth:  Again, I don't understand exactly what you are asking.  Yes, the code is exactly what you see above.  There is no TeensyDebug.h involved.    What board options do you mean?  I don't even know how to select debug in the Arduino IDE.