Unable to start program if org.eclipse.debug.terminal is in the target platform

[iloveeclipse]

Latest master, on Windows 11.

1. Import org.eclipse.debug.terminal into the workspace
2. Start Eclipse from Eclipse
3. Try to debug any trivial Java program like

import javax.swing.JOptionPane;
public class SomeClass {
	public static void main(String[] args) throws Exception {
		JOptionPane.showMessageDialog(null, "Hello, World!");
		while (true) {
			System.err.println(".");
			Thread.sleep(5000);
		}
	}
}

Error will be reported, nothing will be started.
Sometimes Console is opened & some process is shown in debugger but Console doesn't show any output, and debugger doesn't connect.

eclipse.buildId=4.39.0.I20260116-1800
java.version=25.0.1
java.vendor=Oracle Corporation
BootLoader constants: OS=win32, ARCH=x86_64, WS=win32, NL=de_DE
Framework arguments:  -product org.eclipse.sdk.ide
Command-line arguments:  -product org.eclipse.sdk.ide -data C:\eclipse\workspaces\platform/../runtime-Java25 -dev file:///C:/eclipse/workspaces/platform/.metadata/.plugins/org.eclipse.pde.core/Java25/dev.properties -os win32 -ws win32 -arch x86_64 -consoleLog

org.eclipse.jdt.launching
Error
Sun Jan 18 17:41:17 CET 2026
Cannot connect to VM

java.net.SocketException: Socket closed
	at java.base/sun.nio.ch.NioSocketImpl.endAccept(NioSocketImpl.java:685)
	at java.base/sun.nio.ch.NioSocketImpl.accept(NioSocketImpl.java:758)
	at java.base/java.net.ServerSocket.implAccept(ServerSocket.java:593)
	at java.base/java.net.ServerSocket.platformImplAccept(ServerSocket.java:560)
	at java.base/java.net.ServerSocket.implAccept(ServerSocket.java:536)
	at java.base/java.net.ServerSocket.implAccept(ServerSocket.java:482)
	at java.base/java.net.ServerSocket.accept(ServerSocket.java:441)
	at org.eclipse.jdi.internal.connect.SocketTransportService.accept(SocketTransportService.java:91)
	at org.eclipse.jdi.internal.connect.SocketTransportImpl.accept(SocketTransportImpl.java:63)
	at org.eclipse.jdi.internal.connect.SocketListeningConnectorImpl.accept(SocketListeningConnectorImpl.java:167)
	at org.eclipse.jdt.internal.launching.StandardVMDebugger$ConnectRunnable.run(StandardVMDebugger.java:113)
	at java.base/java.lang.Thread.run(Thread.java:1474)

4. Close org.eclipse.debug.terminal project, restart Eclipse and run same config - everything works.
5. Similar happens with the batch file executed as "external program"

@echo off
echo Hello World
pause

The change is related to 67a55ce / #1763.

What I miss is any reasonable possibility to disable this behavior from the launch configuration.

There is a new options group "Allocate console | Allocate terminal | Disable Input/Output" added in the launch config that probably is supposed to control this behavior, but it simply doesn't make any difference which option I select, nothing changes.

Only way I found to "fix" the problem is to disable output merging which results in this code below executed that prevents PTY to be created:

https://github.com/eclipse-platform/eclipse.platform/blob/master/debug/org.eclipse.debug.terminal/src/org/eclipse/debug/terminal/PtyExecFactory.java#L33-L35

But this is surely not "right" way to deal with that problem.

[laeubi]

There is a new options group "Allocate console | Allocate terminal | Disable Input/Output" added in the launch config that probably is supposed to control this behavior, but it simply doesn't make any difference which option I select, nothing changes.

Then something is wrong there. If you select "Allocate Text Console" then the exe factory should not be set and therefore should not do anything.

Beside that I found that under windows the PTY is not able to work together with the way how Eclipse starts java processes there but have not yet found why (maybe java.exe vs javaw.exe ...)