Error using LSP: `Erlang error: {:erpc, :noconnection}`

[zachdaniel]

Environment:

OS: Mac OS Tahoe & Sequoia (another person here next to me has the same issue)
Elixir: 1.18.4
Erlang: 27.1.2
Editor: Zed & Neovim (same error)
Installation Method: Both the gh CLI & building from source
Affected components: any call to the LSP it appears.

Erlang error: {:erpc, :noconnection}
    (kernel 10.2.7.1) erpc.erl:1376: :erpc.call/5
    (xp_expert 0.1.0-04cd32c) lib/expert/code_intelligence/completion.ex:84: XPExpert.CodeIntelligence.Completion.completions/3
    (xp_expert 0.1.0-04cd32c) lib/expert/code_intelligence/completion.ex:36: XPExpert.CodeIntelligence.Completion.complete/4
    (xp_expert 0.1.0-04cd32c) lib/expert/provider/handlers/completion.ex:21: XPExpert.Provider.Handlers.Completion.handle/2
    (xp_expert 0.1.0-04cd32c) lib/expert.ex:90: XPExpert.handle_request/2
    (xp_gen_lsp 0.11.0) lib/gen_lsp.ex:372: anonymous fn/2 in XPGenLSP.loop/3
    (xp_telemetry 1.3.0) /home/runner/work/expert/expert/apps/expert/deps/telemetry/src/telemetry.erl:324: :xp_telemetry.span/3
    (xp_gen_lsp 0.11.0) lib/gen_lsp.ex:371: anonymous fn/5 in XPGenLSP.loop/3

I'm aware this is a nightly build and hiccups are to be expected, so thanks once again for all your hard work, hopefully this issue is helpful! I'm at your disposal if you need any other information, and apologies if I didn't install it right, it is very possible 😆

[zachdaniel]

Zed configuration:

  "lsp": {
    "elixir-ls": {
      "binary": {
        "path": "/Users/zachdaniel/dev/oss/expert/expert_darwin_arm64",
        "arguments": ["start"] # tried with and without this
      }
      // "settings": {
      //   "dialyzerEnabeld": true,
      //   "incrementalDialyzer": true,
      //   "enableTestLenses": false,
      //   "fetchDeps": false
      // }
    }
  },

[zachdaniel]

Looks like this doesn't happen in a new small package, but it does happen in the Ash codebase (sorry).

[zachdaniel]

  "languages": {
    "Elixir": {
      "language_servers": ["expert"]
    }
  },

This is the setup that works now for the smaller project as of the latest elixir extension release.

[salfum]

Can reproduce this error when elixir 1.14.3 is used in a project (asdf set elixir 1.14.3).
With asdf set elixir 1.18.4 everything works as expected.
Erlang: 26.2.2

[siricard]

Same error for me. Adding some info in case this could help
OS: MacOS Sequoia 15.5
Expert: compiled with Elixir 1.16.3, Erlang/OTP 26
Project: compiled with Elixir 1.16.3, Erlang/OTP 26

Using Neovim:

** (ErlangError) Erlang error: {:erpc, :noconnection}
        (kernel 9.2.4.6) erpc.erl:710: :erpc.call/5
        (xp_expert 0.1.0) lib/expert/provider/handlers/hover.ex:27: XPExpert.Provider.Handlers.Hover.handle/2
        (xp_expert 0.1.0) lib/expert.ex:94: XPExpert.handle_request/2
        (xp_gen_lsp 0.11.0) lib/gen_lsp.ex:372: anonymous fn/2 in XPGenLSP.loop/3
        (xp_telemetry 1.3.0) /Users/simonricard/Dev/expert/apps/expert/deps/telemetry/src/telemetry.erl:324: :xp_ telemetry.span/3
        (xp_gen_lsp 0.11.0) lib/gen_lsp.ex:371: anonymous fn/5 in XPGenLSP.loop/3
        (xp_gen_lsp 0.11.0) lib/gen_lsp.ex:601: anonymous fn/4 in XPGenLSP.attempt/4
        (elixir 1.16.3) lib/task/supervised.ex:101: Task.Supervised.invoke_mfa/2"

Thanks again for your work! ❤️

[oliver-kriska]

Same error with larger codebase.

Zed Preview 0.202.2
Elixir 1.18.4 (compiled with Erlang/OTP 27)
Erlang/OTP 27 [erts-15.2.7]
MacOS Sequoia 15.6.1
nightly build installed by Zed Extension

Configuration in Zed:

 "languages": {
    "Elixir": {
      "language_servers": [
        "expert",
        "!elixir-ls",
        "!next-ls",
        "!lexical",
        "..."
      ]
      // "format_on_save": {
      //   "external": {
      //     "command": "mix",
      //     "arguments": ["format", "--stdin-filename", "{buffer_path}", "-"]
      //   }
      // }
    }
  },

When I uncomment "format_on_save", it's complaining about unknown command mix. Not sure if it's issue in Zed or in expert.

Same with manual build from main, see log:

07:30:01.161 [debug] sent notification server -> client window/logMessage
07:30:01.161 [debug] handled request client -> server textDocument/definition in 182µs
07:30:01.209 [debug] sent notification server -> client window/logMessage
07:30:01.209 [debug] handled request client -> server textDocument/definition in 150µs
07:30:01.211 [debug] handled notification client -> server $/cancelRequest in 37µs
07:30:01.504 [debug] sent notification server -> client window/logMessage
07:30:01.504 [debug] handled request client -> server textDocument/definition in 178µs
07:30:01.612 [debug] handled notification client -> server $/cancelRequest in 80µs
07:30:01.713 [debug] sent notification server -> client window/logMessage
07:30:01.713 [debug] handled request client -> server textDocument/codeAction in 417µs
07:30:01.723 [debug] sent notification server -> client window/logMessage
07:30:01.723 [debug] handled request client -> server textDocument/hover in 220µs
07:30:01.847 [debug] sent notification server -> client window/logMessage
07:30:01.847 [debug] handled request client -> server textDocument/definition in 289µs
07:30:01.984 [debug] handled notification client -> server $/cancelRequest in 113µs
07:30:02.188 [debug] handled notification client -> server $/cancelRequest in 70µs
07:30:02.207 [error] ** (ErlangError) Erlang error: {:erpc, :noconnection}
    (kernel 10.2.7.1) erpc.erl:1376: :erpc.call/5
    (elixir 1.17.3) lib/enum.ex:987: Enum."-each/2-lists^foreach/1-0-"/2
    (xp_expert 0.1.0-57abaff) lib/expert/state.ex:196: XPExpert.State.apply/2
    (xp_expert 0.1.0-57abaff) lib/expert.ex:200: XPExpert.apply_to_state/2
    (xp_expert 0.1.0-57abaff) lib/expert.ex:139: XPExpert.handle_notification/2
    (xp_gen_lsp 0.11.0) lib/gen_lsp.ex:528: anonymous fn/2 in XPGenLSP.loop/3
    (xp_telemetry 1.3.0) /home/runner/work/expert/expert/apps/expert/deps/telemetry/src/telemetry.erl:324: :xp_telemetry.span/3
    (xp_gen_lsp 0.11.0) lib/gen_lsp.ex:524: anonymous fn/4 in XPGenLSP.loop/3

07:30:02.207 [debug] sent notification server -> client window/logMessage
07:30:02.207 [warning] client -> server notification crashed
07:30:02.208 [error] ** (ErlangError) Erlang error: {:erpc, :noconnection}
    (kernel 10.2.7.1) erpc.erl:1376: :erpc.call/5
    (xp_expert 0.1.0-57abaff) lib/expert/state.ex:171: XPExpert.State.apply/2
    (xp_expert 0.1.0-57abaff) lib/expert.ex:200: XPExpert.apply_to_state/2
    (xp_expert 0.1.0-57abaff) lib/expert.ex:139: XPExpert.handle_notification/2
    (xp_gen_lsp 0.11.0) lib/gen_lsp.ex:528: anonymous fn/2 in XPGenLSP.loop/3
    (xp_telemetry 1.3.0) /home/runner/work/expert/expert/apps/expert/deps/telemetry/src/telemetry.erl:324: :xp_telemetry.span/3
    (xp_gen_lsp 0.11.0) lib/gen_lsp.ex:524: anonymous fn/4 in XPGenLSP.loop/3
    (xp_gen_lsp 0.11.0) lib/gen_lsp.ex:601: anonymous fn/4 in XPGenLSP.attempt/4

07:30:02.208 [debug] sent notification server -> client window/logMessage
07:30:02.208 [warning] client -> server notification crashed
07:30:03.846 [debug] handled notification client -> server $/cancelRequest in 230µs
07:30:03.849 [error] ** (ErlangError) Erlang error: {:erpc, :noconnection}
    (kernel 10.2.7.1) erpc.erl:1376: :erpc.call/5
    (elixir 1.17.3) lib/enum.ex:987: Enum."-each/2-lists^foreach/1-0-"/2
    (xp_expert 0.1.0-57abaff) lib/expert/state.ex:196: XPExpert.State.apply/2
    (xp_expert 0.1.0-57abaff) lib/expert.ex:200: XPExpert.apply_to_state/2
    (xp_expert 0.1.0-57abaff) lib/expert.ex:139: XPExpert.handle_notification/2
    (xp_gen_lsp 0.11.0) lib/gen_lsp.ex:528: anonymous fn/2 in XPGenLSP.loop/3
    (xp_telemetry 1.3.0) /home/runner/work/expert/expert/apps/expert/deps/telemetry/src/telemetry.erl:324: :xp_telemetry.span/3
    (xp_gen_lsp 0.11.0) lib/gen_lsp.ex:524: anonymous fn/4 in XPGenLSP.loop/3

07:30:03.849 [debug] sent notification server -> client window/logMessage
07:30:03.849 [warning] client -> server notification crashed
07:30:03.869 [error] ** (ErlangError) Erlang error: {:erpc, :noconnection}
    (kernel 10.2.7.1) erpc.erl:1376: :erpc.call/5
    (xp_expert 0.1.0-57abaff) lib/expert/state.ex:171: XPExpert.State.apply/2
    (xp_expert 0.1.0-57abaff) lib/expert.ex:200: XPExpert.apply_to_state/2
    (xp_expert 0.1.0-57abaff) lib/expert.ex:139: XPExpert.handle_notification/2
    (xp_gen_lsp 0.11.0) lib/gen_lsp.ex:528: anonymous fn/2 in XPGenLSP.loop/3
    (xp_telemetry 1.3.0) /home/runner/work/expert/expert/apps/expert/deps/telemetry/src/telemetry.erl:324: :xp_telemetry.span/3
    (xp_gen_lsp 0.11.0) lib/gen_lsp.ex:524: anonymous fn/4 in XPGenLSP.loop/3
    (xp_gen_lsp 0.11.0) lib/gen_lsp.ex:601: anonymous fn/4 in XPGenLSP.attempt/4

07:30:03.869 [debug] sent notification server -> client window/logMessage
07:30:03.869 [warning] client -> server notification crashed
07:30:12.446 [debug] handled notification client -> server workspace/didChangeConfiguration in 144µs
07:30:12.456 [debug] handled notification client -> server workspace/didChangeConfiguration in 98µs
07:30:18.465 [debug] handled notification client -> server $/cancelRequest in 149µs
07:30:18.839 [debug] sent notification server -> client window/logMessage
07:30:18.839 [debug] handled request client -> server textDocument/codeAction in 1ms

FYI I changed manually what Zed use:

~/Library/Application Support/Zed/extensions/work/elixir/expert-nightly
❯ lsa
total 64936
drwxr-xr-x@ 6 oliverkriska  staff   192B Aug 29 07:26 .
drwxr-xr-x@ 3 oliverkriska  staff    96B Aug 29 06:45 ..
drwxr-xr-x@ 3 oliverkriska  staff    96B Aug 29 07:26 .expert
lrwxr-xr-x@ 1 oliverkriska  staff    79B Aug 29 07:26 expert -> /Users/oliverkriska/Projects/expert/apps/expert/burrito_out/expert_darwin_arm64
-rwxr-xr-x@ 1 oliverkriska  staff    31M Aug 29 06:45 expert-n

[falood]

expert-darwin-arm64 by just release-local from current main(b984bcb), and I got similar error

myapp (expert): ** (ErlangError) Erlang error: {:erpc, :noconnection}
    (kernel 10.2.6) erpc.erl:1376: :erpc.call/5
    (xp_expert 0.1.0) lib/expert/code_intelligence/completion.ex:84: XPExpert.CodeIntelligence.Completion.completions/3
    (xp_expert 0.1.0) lib/expert/code_intelligence/completion.ex:36: XPExpert.CodeIntelligence.Completion.complete/4
    (xp_expert 0.1.0) lib/expert/provider/handlers/completion.ex:21: XPExpert.Provider.Handlers.Completion.handle/2
    (xp_expert 0.1.0) lib/expert.ex:94: XPExpert.handle_request/2
    (xp_gen_lsp 0.11.0) lib/gen_lsp.ex:372: anonymous fn/2 in XPGenLSP.loop/3
    (xp_telemetry 1.3.0) /Users/falood/Codes/expert/apps/expert/deps/telemetry/src/telemetry.erl:324: :xp_telemetry.span/3
    (xp_gen_lsp 0.11.0) lib/gen_lsp.ex:371: anonymous fn/5 in XPGenLSP.loop/3

and epmd -names returns

epmd: up and running on port 4369 with data:
name manager-myapp-5348 at port 53514

[rktjmp]

Sorry, kinda a big post,

The second time Expert invokes elixir, $PATH has been wrapped in ' quotes, which prevents it from being correctly interpreted as a PATH specification.

This wrapping removes erl from the $PATH causing a startup failure. This is probably only visible when running mise or asdf as when installing to a system path, erl is still discovered by other means (?).

I have been using b984bcb (built) and 57abaff (nightly). I have no trouble running erl directly from the shell (fish). I have tried installing a few versions of elixir and erlang.

Yes this is manually written even though I appear to have LLM subheadings.

Checking for the error

I noticed that tucked away in all the noconnection noise was a failure to run erl:

nvim lib/file.ex :LspLog and search for exec: erl: not found

or

helix -v lib/file.ex :log-open and seach for exec: erl: not found

Is everyone using mise or asdf?

Note the writing of this error was perhaps a bit sporadic? Perhaps Expert does not always log the failure depending on a race or something. To be clear, Expert would never work, but the error was not always in the log. Maybe it always gets written and I was just quitting too early.

Debugging

I edited /home/<USER>/.local/share/mise/installs/elixir/1.17.3-otp-27/bin/elixir (nvim $(which elixir) in posix) and added the following near the end, just before the exec call:

  echo "INVOCATION" >> /tmp/expert-elixir-cmd
  echo "which-erl: $(which erl)" >> /tmp/expert-elixir-cmd
  echo "type -a erl: $(type -a erl)" >> /tmp/expert-elixir-cmd
  echo "$@" >> /tmp/expert-elixir-cmd
  echo "PATH is >>$PATH<<" >> /tmp/expert-elixir-cmd
  echo "" >> /tmp/expert-elixir-cmd

I also edited erl (nvim (which erl)) and put this at the very start:

echo "INVOCATION $@" >> /tmp/expert-erl-cmd
# echo $(env) >> /tmp/cmd-erl-path
echo $PATH >> /tmp/expert-erl-cmd
echo "" >> /tmp/expert-erl-cmd

Then start your editor & lsp, note that /tmp/expert-elixir-cmd exists, /tmp/expert-erl-cmd does not. I could run the target commands in my shell. These all ran without issue. (Does require manually wrapping the command for -e Node.connect... in quotes.)

Bandaid

If I manually link erl into the system path via

sudo ln -s /home/<USER>/.local/share/mise/installs/erlang/27.3.4.2/bin/erl /usr/local/bin/erl

then Expert functions in neovim and helix without trouble, so that "solves" the "cant exec erl" and "noconnection" issue which is caused by the server never running, so its some kind of $PATH issue.

Thinking...

We can be sure that the mise installed elixir command is running because we see the output in /tmp/expert-elixir-cmd. So we know the editor can run expert, and expert can find elixir in the correct place, but then finding erl somehow gets disrupted.

We can also be sure that when the system path link (/usr/local/bin/erl) is installed our mise installed erl is run (via the symlink) because we see the output in /tmp/expert-erl-cmd, so there is no issue of Expert trying to run some "shipped" executable.

Again, I swear I am a human writing this and they just sound like us.

So examining /tmp/expert-elixir-cmd (Run without the erl symlink!!!) shows something weird, we have two invocations, the first runs fine, erl is picked up in the mise location (as returned by which erl), the second invocation has somehow nuked erl:

INVOCATION
which-erl: /home/soup/.local/share/mise/installs/erlang/27.3.4.2/bin/erl
type -a erl: erl is /home/soup/.local/share/mise/installs/erlang/27.3.4.2/bin/erl
erl -noshell -elixir_root /home/soup/.local/share/mise/installs/elixir/1.17.3-otp-27/bin/../lib -pa /home/soup/.local/share/mise/installs/elixir/1.17.3-otp-27/bin/../lib/elixir/ebin -s elixir start_cli -extra /home/soup/.local/share/.burrito/expert_erts-15.2.7.1_0.1.0/lib/xp_expert-0.1.0/priv/build_engine.exs --source-path /home/soup/.local/share/.burrito/expert_erts-15.2.7.1_0.1.0/lib/xp_expert-0.1.0/priv/engine_source/apps/engine --vsn 0.1.0
/home/soup/.local/share/.burrito/expert_erts-15.2.7.1_0.1.0/erts-15.2.7.1/bin:/home/soup/.local/share/.burrito/expert_erts-15.2.7.1_0.1.0/bin:/home/soup/.local/share/mise/installs/erlang/27.3.4.2/bin:/home/soup/.local/share/mise/installs/elixir/1.17.3-otp-27/bin:/home/soup/.local/share/mise/installs/elixir/1.17.3-otp-27/.mix/escripts:/home/soup/.local/share/mise/installs/node/24.4.0/bin:/home/soup/.local/share/mise/installs/zig/0.14.1/bin:/home/soup/.local/share/mise/installs/usage/2.2.2:/usr/local/sbin:/usr/local/bin:/usr/bin:/usr/bin/site_perl:/usr/bin/vendor_perl:/usr/bin/core_perl:/var/lib/flatpak/exports/bin

INVOCATION
which-erl: 
type -a erl: 
erl -noshell -elixir_root /home/soup/.local/share/mise/installs/elixir/1.17.3-otp-27/bin/../lib -pa /home/soup/.local/share/mise/installs/elixir/1.17.3-otp-27/bin/../lib/elixir/ebin -s elixir start_cli -name project-expert_test-34066@127.0.0.1 -setcookie expert -extra --no-halt -e Node.connect(:"manager-expert_test-34066@127.0.0.1") -pa /home/soup/.local/share/Expert/0.1.0/elixir-1.17.3-erts-15.2.7.1/68796f60c69715a3d1164a6b83e51e36/_build/dev_ns/lib/mix_install/ebin -pa /home/soup/.local/share/Expert/0.1.0/elixir-1.17.3-erts-15.2.7.1/68796f60c69715a3d1164a6b83e51e36/_build/dev_ns/lib/patch/ebin -pa /home/soup/.local/share/Expert/0.1.0/elixir-1.17.3-erts-15.2.7.1/68796f60c69715a3d1164a6b83e51e36/_build/dev_ns/lib/xp_bunt/ebin -pa /home/soup/.local/share/Expert/0.1.0/elixir-1.17.3-erts-15.2.7.1/68796f60c69715a3d1164a6b83e51e36/_build/dev_ns/lib/xp_credo/ebin -pa /home/soup/.local/share/Expert/0.1.0/elixir-1.17.3-erts-15.2.7.1/68796f60c69715a3d1164a6b83e51e36/_build/dev_ns/lib/xp_elixir_sense/ebin -pa /home/soup/.local/share/Expert/0.1.0/elixir-1.17.3-erts-15.2.7.1/68796f60c69715a3d1164a6b83e51e36/_build/dev_ns/lib/xp_engine/ebin -pa /home/soup/.local/share/Expert/0.1.0/elixir-1.17.3-erts-15.2.7.1/68796f60c69715a3d1164a6b83e51e36/_build/dev_ns/lib/xp_file_system/ebin -pa /home/soup/.local/share/Expert/0.1.0/elixir-1.17.3-erts-15.2.7.1/68796f60c69715a3d1164a6b83e51e36/_build/dev_ns/lib/xp_forge/ebin -pa /home/soup/.local/share/Expert/0.1.0/elixir-1.17.3-erts-15.2.7.1/68796f60c69715a3d1164a6b83e51e36/_build/dev_ns/lib/xp_gen_lsp/ebin -pa /home/soup/.local/share/Expert/0.1.0/elixir-1.17.3-erts-15.2.7.1/68796f60c69715a3d1164a6b83e51e36/_build/dev_ns/lib/xp_jason/ebin -pa /home/soup/.local/share/Expert/0.1.0/elixir-1.17.3-erts-15.2.7.1/68796f60c69715a3d1164a6b83e51e36/_build/dev_ns/lib/xp_nimble_options/ebin -pa /home/soup/.local/share/Expert/0.1.0/elixir-1.17.3-erts-15.2.7.1/68796f60c69715a3d1164a6b83e51e36/_build/dev_ns/lib/xp_nimble_parsec/ebin -pa /home/soup/.local/share/Expert/0.1.0/elixir-1.17.3-erts-15.2.7.1/68796f60c69715a3d1164a6b83e51e36/_build/dev_ns/lib/xp_path_glob/ebin -pa /home/soup/.local/share/Expert/0.1.0/elixir-1.17.3-erts-15.2.7.1/68796f60c69715a3d1164a6b83e51e36/_build/dev_ns/lib/xp_refactorex/ebin -pa /home/soup/.local/share/Expert/0.1.0/elixir-1.17.3-erts-15.2.7.1/68796f60c69715a3d1164a6b83e51e36/_build/dev_ns/lib/xp_schematic/ebin -pa /home/soup/.local/share/Expert/0.1.0/elixir-1.17.3-erts-15.2.7.1/68796f60c69715a3d1164a6b83e51e36/_build/dev_ns/lib/xp_snowflake/ebin -pa /home/soup/.local/share/Expert/0.1.0/elixir-1.17.3-erts-15.2.7.1/68796f60c69715a3d1164a6b83e51e36/_build/dev_ns/lib/xp_sourceror/ebin -pa /home/soup/.local/share/Expert/0.1.0/elixir-1.17.3-erts-15.2.7.1/68796f60c69715a3d1164a6b83e51e36/_build/dev_ns/lib/xp_telemetry/ebin -pa /home/soup/.local/share/Expert/0.1.0/elixir-1.17.3-erts-15.2.7.1/68796f60c69715a3d1164a6b83e51e36/_build/dev_ns/lib/xp_typed_struct/ebin
'/home/soup/.local/share/mise/installs/erlang/27.3.4.2/bin:/home/soup/.local/share/mise/installs/elixir/1.17.3-otp-27/bin:/home/soup/.local/share/mise/installs/elixir/1.17.3-otp-27/.mix/escripts:/home/soup/.local/share/mise/installs/node/24.4.0/bin:/home/soup/.local/share/mise/installs/zig/0.14.1/bin:/home/soup/.local/share/mise/installs/usage/2.2.2:/home/soup/.local/share/.burrito/expert_erts-15.2.7.1_0.1.0/erts-15.2.7.1/bin:/home/soup/.local/share/.burrito/expert_erts-15.2.7.1_0.1.0/bin:/usr/local/sbin:/usr/local/bin:/usr/bin:/usr/bin/site_perl:/usr/bin/vendor_perl:/usr/bin/core_perl:/var/lib/flatpak/exports/bin'

Note the differences in the $PATH outputs. The first has burrito in it, and the second doesn't. And, hang on, is that a dust on my screen?

PATH is >>/home/soup/.local/share/.burrito/expert_erts-15.2.7.1_0.1.0/erts-15.2.7.1/bin:/home/soup/.local/share/.burrito/expert_erts-15.2.7.1_0.1.0/bin:/home/soup/.local/share/mise/installs/erlang/27.3.4.2/bin:/home/soup/.local/share/mise/installs/elixir/1.17.3-otp-27/bin:/home/soup/.local/share/mise/installs/elixir/1.17.3-otp-27/.mix/escripts:/home/soup/.local/share/mise/installs/node/24.4.0/bin:/home/soup/.local/share/mise/installs/zig/0.14.1/bin:/home/soup/.local/share/mise/installs/usage/2.2.2:/usr/local/sbin:/usr/local/bin:/usr/bin:/usr/bin/site_perl:/usr/bin/vendor_perl:/usr/bin/core_perl:/var/lib/flatpak/exports/bin<<

PATH is >>'/home/soup/.local/share/mise/installs/erlang/27.3.4.2/bin:/home/soup/.local/share/mise/installs/elixir/1.17.3-otp-27/bin:/home/soup/.local/share/mise/installs/elixir/1.17.3-otp-27/.mix/escripts:/home/soup/.local/share/mise/installs/node/24.4.0/bin:/home/soup/.local/share/mise/installs/zig/0.14.1/bin:/home/soup/.local/share/mise/installs/usage/2.2.2:/home/soup/.local/share/.burrito/expert_erts-15.2.7.1_0.1.0/erts-15.2.7.1/bin:/home/soup/.local/share/.burrito/expert_erts-15.2.7.1_0.1.0/bin:/usr/local/sbin:/usr/local/bin:/usr/bin:/usr/bin/site_perl:/usr/bin/vendor_perl:/usr/bin/core_perl:/var/lib/flatpak/exports/bin'<<

The second $PATH is a has ' characters wrapping it, probably preventing correct interpretation.

We can test fixing this by removing any surrounding quotes from $PATH:

  PATH=${PATH%\'}
  PATH=${PATH#\'}
  echo "INVOCATION" >> /tmp/expert-elixir-cmd
  echo "which-erl: $(which erl)" >> /tmp/expert-elixir-cmd
  echo "type -a erl: $(type -a erl)" >> /tmp/expert-elixir-cmd
  echo "$@" >> /tmp/expert-elixir-cmd
  echo "PATH is >>$PATH<<" >> /tmp/expert-elixir-cmd
  echo "" >> /tmp/expert-elixir-cmd
  exec "$@"

Now rerunning (remember, remove the /usr/local/bin symlink), we can see:

INVOCATION
which-erl: /home/soup/.local/share/mise/installs/erlang/27.3.4.2/bin/erl
type -a erl: erl is /home/soup/.local/share/mise/installs/erlang/27.3.4.2/bin/erl
erl -noshell -elixir_root /home/soup/.local/share/mise/installs/elixir/1.17.3-otp-27/bin/../lib -pa /home/soup/.local/share/mise/installs/elixir/1.17.3-otp-27/bin/../lib/elixir/ebin -s elixir start_cli -extra /home/soup/.local/share/.burrito/expert_erts-15.2.7.1_0.1.0/lib/xp_expert-0.1.0/priv/build_engine.exs --source-path /home/soup/.local/share/.burrito/expert_erts-15.2.7.1_0.1.0/lib/xp_expert-0.1.0/priv/engine_source/apps/engine --vsn 0.1.0
PATH is >>/home/soup/.local/share/.burrito/expert_erts-15.2.7.1_0.1.0/erts-15.2.7.1/bin:/home/soup/.local/share/.burrito/expert_erts-15.2.7.1_0.1.0/bin:/home/soup/.local/share/mise/installs/erlang/27.3.4.2/bin:/home/soup/.local/share/mise/installs/elixir/1.17.3-otp-27/bin:/home/soup/.local/share/mise/installs/elixir/1.17.3-otp-27/.mix/escripts:/home/soup/.local/share/mise/installs/node/24.4.0/bin:/home/soup/.local/share/mise/installs/zig/0.14.1/bin:/home/soup/.local/share/mise/installs/usage/2.2.2:/usr/local/sbin:/usr/local/bin:/usr/bin:/usr/bin/site_perl:/usr/bin/vendor_perl:/usr/bin/core_perl:/var/lib/flatpak/exports/bin<<

INVOCATION
which-erl: /home/soup/.local/share/mise/installs/erlang/27.3.4.2/bin/erl
type -a erl: erl is /home/soup/.local/share/mise/installs/erlang/27.3.4.2/bin/erl
erl -noshell -elixir_root /home/soup/.local/share/mise/installs/elixir/1.17.3-otp-27/bin/../lib -pa /home/soup/.local/share/mise/installs/elixir/1.17.3-otp-27/bin/../lib/elixir/ebin -s elixir start_cli -name project-expert_test-50814@127.0.0.1 -setcookie expert -extra --no-halt -e Node.connect(:"manager-expert_test-50814@127.0.0.1") -pa /home/soup/.local/share/Expert/0.1.0/elixir-1.17.3-erts-15.2.7.1/68796f60c69715a3d1164a6b83e51e36/_build/dev_ns/lib/mix_install/ebin -pa /home/soup/.local/share/Expert/0.1.0/elixir-1.17.3-erts-15.2.7.1/68796f60c69715a3d1164a6b83e51e36/_build/dev_ns/lib/patch/ebin -pa /home/soup/.local/share/Expert/0.1.0/elixir-1.17.3-erts-15.2.7.1/68796f60c69715a3d1164a6b83e51e36/_build/dev_ns/lib/xp_bunt/ebin -pa /home/soup/.local/share/Expert/0.1.0/elixir-1.17.3-erts-15.2.7.1/68796f60c69715a3d1164a6b83e51e36/_build/dev_ns/lib/xp_credo/ebin -pa /home/soup/.local/share/Expert/0.1.0/elixir-1.17.3-erts-15.2.7.1/68796f60c69715a3d1164a6b83e51e36/_build/dev_ns/lib/xp_elixir_sense/ebin -pa /home/soup/.local/share/Expert/0.1.0/elixir-1.17.3-erts-15.2.7.1/68796f60c69715a3d1164a6b83e51e36/_build/dev_ns/lib/xp_engine/ebin -pa /home/soup/.local/share/Expert/0.1.0/elixir-1.17.3-erts-15.2.7.1/68796f60c69715a3d1164a6b83e51e36/_build/dev_ns/lib/xp_file_system/ebin -pa /home/soup/.local/share/Expert/0.1.0/elixir-1.17.3-erts-15.2.7.1/68796f60c69715a3d1164a6b83e51e36/_build/dev_ns/lib/xp_forge/ebin -pa /home/soup/.local/share/Expert/0.1.0/elixir-1.17.3-erts-15.2.7.1/68796f60c69715a3d1164a6b83e51e36/_build/dev_ns/lib/xp_gen_lsp/ebin -pa /home/soup/.local/share/Expert/0.1.0/elixir-1.17.3-erts-15.2.7.1/68796f60c69715a3d1164a6b83e51e36/_build/dev_ns/lib/xp_jason/ebin -pa /home/soup/.local/share/Expert/0.1.0/elixir-1.17.3-erts-15.2.7.1/68796f60c69715a3d1164a6b83e51e36/_build/dev_ns/lib/xp_nimble_options/ebin -pa /home/soup/.local/share/Expert/0.1.0/elixir-1.17.3-erts-15.2.7.1/68796f60c69715a3d1164a6b83e51e36/_build/dev_ns/lib/xp_nimble_parsec/ebin -pa /home/soup/.local/share/Expert/0.1.0/elixir-1.17.3-erts-15.2.7.1/68796f60c69715a3d1164a6b83e51e36/_build/dev_ns/lib/xp_path_glob/ebin -pa /home/soup/.local/share/Expert/0.1.0/elixir-1.17.3-erts-15.2.7.1/68796f60c69715a3d1164a6b83e51e36/_build/dev_ns/lib/xp_refactorex/ebin -pa /home/soup/.local/share/Expert/0.1.0/elixir-1.17.3-erts-15.2.7.1/68796f60c69715a3d1164a6b83e51e36/_build/dev_ns/lib/xp_schematic/ebin -pa /home/soup/.local/share/Expert/0.1.0/elixir-1.17.3-erts-15.2.7.1/68796f60c69715a3d1164a6b83e51e36/_build/dev_ns/lib/xp_snowflake/ebin -pa /home/soup/.local/share/Expert/0.1.0/elixir-1.17.3-erts-15.2.7.1/68796f60c69715a3d1164a6b83e51e36/_build/dev_ns/lib/xp_sourceror/ebin -pa /home/soup/.local/share/Expert/0.1.0/elixir-1.17.3-erts-15.2.7.1/68796f60c69715a3d1164a6b83e51e36/_build/dev_ns/lib/xp_telemetry/ebin -pa /home/soup/.local/share/Expert/0.1.0/elixir-1.17.3-erts-15.2.7.1/68796f60c69715a3d1164a6b83e51e36/_build/dev_ns/lib/xp_typed_struct/ebin
PATH is >>/home/soup/.local/share/mise/installs/erlang/27.3.4.2/bin:/home/soup/.local/share/mise/installs/elixir/1.17.3-otp-27/bin:/home/soup/.local/share/mise/installs/elixir/1.17.3-otp-27/.mix/escripts:/home/soup/.local/share/mise/installs/node/24.4.0/bin:/home/soup/.local/share/mise/installs/zig/0.14.1/bin:/home/soup/.local/share/mise/installs/usage/2.2.2:/home/soup/.local/share/.burrito/expert_erts-15.2.7.1_0.1.0/erts-15.2.7.1/bin:/home/soup/.local/share/.burrito/expert_erts-15.2.7.1_0.1.0/bin:/usr/local/sbin:/usr/local/bin:/usr/bin:/usr/bin/site_perl:/usr/bin/vendor_perl:/usr/bin/core_perl:/var/lib/flatpak/exports/bin<<

It works!

As to where this happens, I am not sure but it's probably a dead easy mistake to make. The path is altered at some point by burrito, perhaps it does not put it back nicely?

[dabaer]

Similar errors to above and in a large codebase, but we're running on Elixir 1.17.3:

2025-08-29T09:34:58-06:00 ERROR [project] Get definition via expert failed: ** (ErlangError) Erlang error: {:erpc, :noconnection}
    (kernel 10.2.7.1) erpc.erl:1376: :erpc.call/5
    (xp_expert 0.1.0-57abaff) lib/expert/provider/handlers/go_to_definition.ex:17: XPExpert.Provider.Handlers.GoToDefinition.handle/2
    (xp_expert 0.1.0-57abaff) lib/expert.ex:94: XPExpert.handle_request/2
    (xp_gen_lsp 0.11.0) lib/gen_lsp.ex:372: anonymous fn/2 in XPGenLSP.loop/3
    (xp_telemetry 1.3.0) /home/runner/work/expert/expert/apps/expert/deps/telemetry/src/telemetry.erl:324: :xp_telemetry.span/3
    (xp_gen_lsp 0.11.0) lib/gen_lsp.ex:371: anonymous fn/5 in XPGenLSP.loop/3
    (xp_gen_lsp 0.11.0) lib/gen_lsp.ex:601: anonymous fn/4 in XPGenLSP.attempt/4
    (elixir 1.17.3) lib/task/supervised.ex:101: Task.Supervised.invoke_mfa/2

[doorgan]

@zachdaniel @salfum can you try again with the latest main when you get a sec? I'm not able to reproduce it with Zed and ash anymore

Also for everyone, can you specify how was elixir/erlang install in your systems? asdf, mise, something else?