Integrated terminal fails with native exception / forkpty(3) failed

[ljwobker]

• VSCode Version: 1.52.1
• Local OS Version: Windows 10 Professional
• Remote OS Version: Linux node0_RP1_CPU0 4.8.28-WR9.0.0.20_cgl
• Remote Extension/Connection Type: SSH

Steps to Reproduce:

1. Connect to remote system. VSCode successfully installs the server remotely, but will not launch a terminal.
2. The following error message appears:
   The terminal process failed to launch: A native exception occurred during launch (forkpty(3) failed.).

Details:
As far as I can tell, the only impacted component is the terminal. The remote filesystem can be seen, files can be edited, etc. I feel as if there must be something unique about this remote, but I can't find any other meaningful debugging or logging output. Would appreciate thoughts on what else to look at / report...

[Aurora28]

Hi, I encountered the same problem but suddenly the error was eliminated from nowhere and the terminal can run successfully. It's kind of weird, so I guess the network stability might matter a lot in this case.

Also What I did:
Open the Settings -> search:terminal.integrated -> find the "Automation Shell: Linux" -> choose "Edit in settings.json"

However, before I did any other further steps, the problem disappeared. So I highly suspect this "forkpty(3) failed" error is closely associated with the internet connection. Just have a try later may help. Good luck :)

[ljwobker]

It's something related to that particular machine type. Other "pure" linux machines in the same lab (i.e. network connectivity) work fine - there's something specific to this distribution or setup, but I don't know what other debugging tools (either on the vscode or linux host side) to look at.

[Josersanvil]

I'm having this same problem, same VSCode version and OS, my remote host is on Ubuntu 18.04.
It started happening after VStudio Code crashed when the terminal was handling a large download process and writing a lot of messages to stdout. Now I can't open the terminal on the remote host.

It doesn't seem to have nothing to do with my network connection either.

[Josersanvil]

I managed to fix it by connecting via SSH to the remote host and manually deleting the ~/.vscode folder, then i set up the connection again on VS Code and it worked fine.

[Tushar1729-k]

Steps to reproduce:

1. I had an infinite loop and a single letter kept printing to stdout and the terminal.
2. Control-c does not stop the process, nor does pressing the trash can button. VSCode simply freezes. It gives a prompt saying you can wait or reopen the window. Upon reopening, this error appears.
3. The same error message appears as OP.

@Josersanvil I tried your fix and unfortunately it did not work for me.

[Tushar1729-k]

FIX
Credit: My TA Kevin
Similar to what @Josersanvil says, delete the ~/.vscode-server folder on the remote host. (It is a hidden folder, so unhide it.)
I added the extra step of reinstalling the Microsoft Remote - SSH extension.
Terminal is happy now.

[tonymurray]

I had similar issue while connecting to a linux host via ssh -- in a chroot environment. [forkpty(3)] failed. I found this: https://unix.stackexchange.com/questions/390997/ptys-not-working-in-chroot-under-lxc. The solution for me was to get pty working within the chroot [ref: https://man7.org/linux/man-pages/man7/pty.7.html] - by creating /chroot/dev device files [ref: https://tldp.org/LDP/Linux-Filesystem-Hierarchy/html/dev.html]. This involved recreating /dev/ptmx and /dev/pts/* (refer to actual (non-chroot) /dev folder). Guide: https://www.lifewire.com/linux-system-administrators-guide-2203428. Regarding permissions: https://lwn.net/Articles/684005/

[Tyriar]

This is where that exception comes from: https://github.com/microsoft/node-pty/blob/87990b27a51423efcd6aa55f32a7b02a972201a7/src/unix/pty.cc#L717

I don't think there's anything I can do on my side here, it's either:

1. A problem with file permissions inside the server install directory as indicated by deleting and reconnecting fixing the issue
2. An OS-level issue out of the scope of vscode

[daniel-oelert]

I have the exact same issue. So far I have tested disabling the TypeScript extension (there were related errors, due to not being able to fork), which didn't help. I even did a clean reinstall of Ubuntu 18.04 Server, with just a user added and ssh configured, nothing else. It also affects more than just VSCode. It renders the server unable to fork at all at times, so i can not use ssh from another terminal to connect to it either. I can easily reproduce the error, can I provide additional information to solve this issue?

[prafiny]

I have been having the same problem on a Linux 4.19.0-14-amd64 #1 SMP Debian 4.19.171-2 (2021-01-30) x86_64 GNU/Linux. Turned out there were wrong /dev/pts permission issues and this was solved by chmoding a+x. Anyways, debugging was tedious for this one as the ERRNO for forkpty wasn't displayed.

[ljwobker]

A colleague was able to track this down (finally). On the target machine in question the permissions for /dev/pts/ptmx were set to something that was unfriendly to VSCode. Changing these permissions allowed the terminal to launch without problems. This level of OS-gookery is beyond my knowledge, so if anyone feels like posting as to why this actually helps that would be great...

[/home/luser]$ ls -l /dev/pts/ptmx
c---------. 1 root root 5, 2 Mar 27 01:22 /dev/pts/ptmx
## no worky!

[/home/luser]$ chmod o+rw /dev/pts/ptmx

[/home/luser]$ ls -l /dev/pts/ptmx
c------rw-. 1 root root 5, 2 Mar 27 01:23 /dev/pts/ptmx
## works now!

[readren]

I have the exact same problem with VSC Version 1.55.2 and Remote SSH version 0.65.4 when connecting from windows 10 to a virtual Centos 7 (Linux 3.10.0-1127.19.1.el7.x86_64) hosted by GCP, using IdentityFile authentication.
It didn't happen the first time I connected, but all the following times.
It is worth clarifying that I am asked to enter the passphrase twice: after "connect to host" and after pressing the "open folder" button.
Neither deleting the "~/.vscode-server" folder nor the applying the "cmod o+rw /dev/pts/ptmx" command did solve it.

[parish-shrestha]

I'm getting this same error.
VSC Version 1.56
Connecting from Windows 10 to a remote host Centos 8 using password.

[matteocostantini]

I'm getting this same error.
VSC Version 1.56.2
Connecting from Windows 10 to a remote host Debian 10 using private key. The user is jailed with jailkit.