lldb-server fails to connect on version 20.1+

[azais-corentin]

Hello,

Since LLVM 20, I'm not able to use remote debugging anymore.

I start the server on one terminal:

lldb-server-20 platform --server --listen *:1234 --min-gdbserver-port 31400 --max-gdbserver-port 31500

Then when I connect, I get the following errors:

> lldb-20
> (lldb) platform select remote-linux
> (lldb) platform connect connect://127.0.0.1:1234
> error: spawn_process failed: execve failed: No such file or directory
> error: Connection shut down by remote side while waiting for reply to initial handshake packet

The exact same steps on LLVM 19 work without any errors.

Please note that the issue seems to be specific to lldb-server since using lldb-20 with lldb-server-19 works.

[llvmbot]

@llvm/issue-subscribers-lldb

Author: Azais Corentin (azais-corentin)

Hello,

Since LLVM 20, I'm not able to use remote debugging anymore.

I start the server on one terminal:

lldb-server-20 platform --server --listen *:1234 --min-gdbserver-port 31400 --max-gdbserver-port 31500

Then when I connect, I get the following errors:

> lldb-20
> (lldb) platform select remote-linux
> (lldb) platform connect connect://127.0.0.1:1234
> error: spawn_process failed: execve failed: No such file or directory
> error: Connection shut down by remote side while waiting for reply to initial handshake packet

The exact same steps on LLVM 19 work without any errors.

Please note that the issue seems to be specific to lldb-server since using lldb-20 with lldb-server-19 works.

[DavidSpickett]

I think this may have been fixed by #131519.

This solves an issue where running lldb-server-20 with a non-absolute path (for example, when it's installed into /usr/bin and the user runs it as lldb-server-20 ... and not /usr/bin/lldb-server-20 ...) fails with error: spawn_process failed: execve failed: No such file or directory.

The issue fixed in the PR we're currently writing in is a regression introduced in LLVM 20 due to a fundamental change in how lldb-server platform mode works, and so it doesn't make sense to me that it existed 2 years ago.

So if you are able to build a new lldb from the main branch, you can check whether this is the case.

[DavidSpickett]

I think we should be backporting that change to the 20 branch anyway, so I've requested that. If it fixes this issue too, that's a bonus.

[azais-corentin]

I tried on LLVM 20.1.1 and using it with an absolute path seems to fix the issue.

I will close this as the two issues are very likely to be the same.

Thanks for your help!

[DavidSpickett]

I reproduced the issue locally and confirmed that a combination of #131519 and #133093 fixes the problem.

How to reproduce:

• Build lldb
• ninja install
• Make a symlink lldb-server-20 in the install dir
• Make sure you are somewhere other than the install dir
• Run the server command using the name lldb-server-20