Start-DebugAttachSession without parameters "hangs"

[nightroman]

Prerequisites

• I have written a descriptive issue title.
• I have searched all open and closed issues to ensure it has not already been reported.
• I have read the troubleshooting guide.
• I am sure this issue is with the extension itself and does not reproduce in a standalone PowerShell instance.
• I have verified that I am using the latest version of Visual Studio Code and the PowerShell extension.
• If this is a security issue, I have read the security issue reporting guidance.

Summary

Start-DebugAttachSession without parameters "hangs".

PowerShell Version

Name                           Value
----                           -----
PSVersion                      7.5.4
PSEdition                      Core
GitCommitId                    7.5.4
OS                             Microsoft Windows 10.0.26200
Platform                       Win32NT
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0…}
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1
WSManStackVersion              3.0

Name             : Visual Studio Code Host
Version          : 2025.5.0
InstanceId       : 34bb8444-87b8-4ee9-862b-d008a055e1c1
UI               : System.Management.Automation.Internal.Host.InternalHostUserInterface
CurrentCulture   : en-GB
CurrentUICulture : en-US
PrivateData      : Microsoft.PowerShell.ConsoleHost+ConsoleColorProxy
DebuggerEnabled  : True
IsRunspacePushed : False
Runspace         : System.Management.Automation.Runspaces.LocalRunspace

Visual Studio Code Version

1.107.0
618725e67565b290ba4da6fe2d29f8fa1d4e3622
x64

Extension Version

ms-vscode.powershell@2025.5.0

Steps to Reproduce

• Start debugging with the PowerShell Interactive profile.
• In the debug terminal invoke Start-DebugAttachSession

Expected result
VSCode shows the dropdown for choosing a process to attach.

Per Start-DebugAttachSession

If -ProcessId or -CustomPipeName is not specified, the debug client will prompt for process to connect to.

Actual result
The command "hangs". Interestingly, when it is terminated by Ctrl+C, the expected dropdown for choosing a process appears, but it's too late, of course, the command is terminated.

[nightroman]

And if/when this issue is fixed then Start-DebugAttachSession should provide a way to return the selected process info to the caller, so that the caller can use Wait-Process, as the sample script does -- ChildDebugSessionAttach.ps1

[andyleejordan]

I honestly had no idea this feature even existed. @jborean93 might be of some help?

[jborean93]

I just stepped through this scenario a bit and it looks like the vscode extension is stuck at

vscode-powershell/src/features/DebugSession.ts

Lines 749 to 752 in 01e8ef8

	const response = await client.sendRequest(
	GetPSHostProcessesRequestType,
	{},
	);

. This seems to be the action powershell/getPSHostProcess which is going to running some commands in PSES but as the main PSES pipeline is still running our debug session it will be waiting indefinitely for the command to finish. This is why when terminating the debug session with Ctrl+C the dropdown then appears.

It looks like we will just have to make the -ProcessId or -CustomPipeName as mandatory and update the documentation to state one of these is required and to remove the part saying VSCode will prompt. I'm curious as to why I added it in the first place but I must have either tested this scenario before the final changes or just not at all.

An alternative would be to figure out a way to have powershell/getPSHostProcess in PSES not use the current runspace through _executionServices.ExecutePSCommandAsync but instead use a separate one dedicated for enumerating the PowerShell processes. It looks like this was done in the past but was changed with PowerShell/PowerShellEditorServices@6cffb4a#diff-b6aa5b193ac18044b8ff5508197e3c12e3b78b055be8c5685f797ffabeed0637 to use the PSES runspace.