Unexpected Failure When Switching to Elixir Version 1.18.4

[wheredoipressnow]

Elixir and Erlang/OTP versions

Elixir 1.18.4 (compiled with Erlang/OTP 27)

Operating system

Windows 11

Current behavior

I recently ran into an issue where ElixirLS version 0.28.0 installs without any problems on Elixir 1.17 but fails when switching to Elixir 1.18.4.

Interestingly, downgrading back to 1.17 immediately resolves the issue.

Below are the relevant logs:

2025-05-28T06:23:19.880 helix_lsp::transport [ERROR] elixir-ls err <- "Installing ElixirLS release v0.28.0\n"
2025-05-28T06:23:19.880 helix_lsp::transport [ERROR] elixir-ls err <- "Running in c:/retracted_internal_name/project_umbrella\n"
2025-05-28T06:23:19.914 helix_lsp::transport [ERROR] elixir-ls err <- "* Updating elixir_ls (https://github.com/elixir-lsp/elixir-ls.git - v0.28.0)\n"
2025-05-28T06:23:21.138 helix_lsp::transport [ERROR] elixir-ls err <- "Mix.install failed with ** (Mix.Error) Command \"git --git-dir=.git checkout --force --quiet v0.28.0\" failed with reason: error: unable to create file apps/language_server/test/fixtures/umbrella_test_code_lens_custom_path_and_pattern/apps/app1/custom_path/fixture_custom_test.exs: Filename too long\n"
2025-05-28T06:23:21.138 helix_lsp::transport [ERROR] elixir-ls err <- "\n"
2025-05-28T06:23:21.138 helix_lsp::transport [ERROR] elixir-ls err <- "    (mix 1.18.4) lib/mix.ex:618: Mix.raise/2\n"
2025-05-28T06:23:21.138 helix_lsp::transport [ERROR] elixir-ls err <- "    (mix 1.18.4) lib/mix/scm/git.ex:140: Mix.SCM.Git.checkout/2\n"
2025-05-28T06:23:21.138 helix_lsp::transport [ERROR] elixir-ls err <- "    (elixir 1.18.4) lib/file.ex:1665: File.cd!/2\n"
2025-05-28T06:23:21.138 helix_lsp::transport [ERROR] elixir-ls err <- "    (mix 1.18.4) lib/mix/dep/fetcher.ex:65: Mix.Dep.Fetcher.do_fetch/3\n"
2025-05-28T06:23:21.138 helix_lsp::transport [ERROR] elixir-ls err <- "    (mix 1.18.4) lib/mix/dep/converger.ex:238: Mix.Dep.Converger.all/9\n"
2025-05-28T06:23:21.138 helix_lsp::transport [ERROR] elixir-ls err <- "    (mix 1.18.4) lib/mix/dep/converger.ex:170: Mix.Dep.Converger.init_all/8\n"
2025-05-28T06:23:21.138 helix_lsp::transport [ERROR] elixir-ls err <- "    (mix 1.18.4) lib/mix/dep/converger.ex:110: Mix.Dep.Converger.all/4\n"
2025-05-28T06:23:21.138 helix_lsp::transport [ERROR] elixir-ls err <- "    (mix 1.18.4) lib/mix/dep/converger.ex:89: Mix.Dep.Converger.converge/4\n"
2025-05-28T06:23:21.138 helix_lsp::transport [ERROR] elixir-ls err <- "\n"
2025-05-28T06:23:21.138 helix_lsp::transport [ERROR] elixir-ls err <- "Retrying Mix.install with force: true\n"
2025-05-28T06:23:21.139 helix_lsp::transport [ERROR] elixir-ls err <- "Installing ElixirLS release v0.28.0\n"
2025-05-28T06:23:21.139 helix_lsp::transport [ERROR] elixir-ls err <- "Running in c:/retracted_internal_name/project_umbrella\n"
2025-05-28T06:23:21.375 helix_lsp::transport [ERROR] elixir-ls err <- "* Getting elixir_ls (https://github.com/elixir-lsp/elixir-ls.git - v0.28.0)\n"
2025-05-28T06:23:24.481 helix_lsp::transport [ERROR] elixir-ls err <- "** (Mix.Error) Command \"git --git-dir=.git checkout --force --quiet v0.28.0\" failed with reason: error: unable to create file apps/language_server/test/fixtures/umbrella_test_code_lens_custom_path_and_pattern/apps/app1/custom_path/fixture_custom_test.exs: Filename too long\n"
2025-05-28T06:23:24.481 helix_lsp::transport [ERROR] elixir-ls err <- "\n"
2025-05-28T06:23:24.481 helix_lsp::transport [ERROR] elixir-ls err <- "    (mix 1.18.4) lib/mix.ex:618: Mix.raise/2\n"
2025-05-28T06:23:24.481 helix_lsp::transport [ERROR] elixir-ls err <- "    (mix 1.18.4) lib/mix/scm/git.ex:140: Mix.SCM.Git.checkout/2\n"
2025-05-28T06:23:24.481 helix_lsp::transport [ERROR] elixir-ls err <- "    (elixir 1.18.4) lib/file.ex:1665: File.cd!/2\n"
2025-05-28T06:23:24.481 helix_lsp::transport [ERROR] elixir-ls err <- "    (mix 1.18.4) lib/mix/dep/fetcher.ex:68: Mix.Dep.Fetcher.do_fetch/3\n"
2025-05-28T06:23:24.481 helix_lsp::transport [ERROR] elixir-ls err <- "    (mix 1.18.4) lib/mix/dep/converger.ex:238: Mix.Dep.Converger.all/9\n"
2025-05-28T06:23:24.481 helix_lsp::transport [ERROR] elixir-ls err <- "    (mix 1.18.4) lib/mix/dep/converger.ex:170: Mix.Dep.Converger.init_all/8\n"
2025-05-28T06:23:24.481 helix_lsp::transport [ERROR] elixir-ls err <- "    (mix 1.18.4) lib/mix/dep/converger.ex:110: Mix.Dep.Converger.all/4\n"
2025-05-28T06:23:24.481 helix_lsp::transport [ERROR] elixir-ls err <- "    (mix 1.18.4) lib/mix/dep/converger.ex:89: Mix.Dep.Converger.converge/4\n"
2025-05-28T06:23:24.496 helix_lsp [ERROR] failed to initialize language server: server closed the stream
2025-05-28T06:23:24.496 helix_lsp::transport [ERROR] elixir-ls err: <- StreamClosed

Expected behavior

I would expect ElixirLS version 0.28.0 to install and function correctly with both Elixir 1.17 and 1.18.4 without issues.

[josevalim]

@wheredoipressnow does it work with Elixir v1.18.3?

@lukaszsamson it is failing because of a really long path. Are those paths part of ElixirLS? Any reason why test files are part of the distributed package?

[wheredoipressnow]

Yes, I can confirm that with Elixir version 1.18.3 it works as expected.

[josevalim]

Thank you. Can you please try this in IEx using v1.18.4:

iex> Mix.install [{:elixir_ls, github: "elixir-lsp/elixir-ls", tag: "v0.28.0"}]

Also please try this in your terminal:

$ git clone https://github.com/elixir-lsp/elixir-ls.git
$ cd elixir-ls
$ git checkout --force --quiet v0.28.0

If it fails with the --force flag, please also try it without the --force flag.

---

@lukaszsamson, here is the Mix diff between Elixir versions. It all points out to the --force flag that we added However, note the error is fully coming from git and it complains about a long filename. According to the docs, Git supports filenames only up to 260 characters, and that particular file is already taking 128 characters. I don't know if the --force flag makes Git behave slightly differently (perhaps it clones it to another directory first, making it go above the file limit). As you know, the --force flag is important to fix the checkout issues, so it is not something we can remove either.

[lukaszsamson]

Are those paths part of ElixirLS? Any reason why test files are part of the distributed package?

Yes, those are tests. ElixirLS uses Mix.install with git dependency which clones the whole repo. Why did it start failing on 1.18.4? The only relevant change was 332ff94 adding --force flag. Could it have been failing silently before?

@wheredoipressnow try enabling long paths in git

git config --system core.longpaths true

[wheredoipressnow]

Long path support in Git resolves the issue. It appears indeed that error was previously silently ignored, as the logs indicate.

Thanks for the help!

With Elixir 1.18.3 or before:

helix_lsp::transport [ERROR] elixir-ls err <- "Installing ElixirLS release v0.28.0\n"
helix_lsp::transport [ERROR] elixir-ls err <- "Running in project_path\n"
helix_lsp::transport [ERROR] elixir-ls err <- "Install complete\n"

Now with Elixir 1.18.4 and long path support in Git enabled:

helix_lsp::transport [ERROR] elixir-ls err <- "Installing ElixirLS release v0.28.0\n"
helix_lsp::transport [ERROR] elixir-ls err <- "Running in project_path\n"
helix_lsp::transport [ERROR] elixir-ls err <- "* Updating elixir_ls (https://github.com/elixir-lsp/elixir-ls.git - v0.28.0)\n"
helix_lsp::transport [ERROR] elixir-ls err <- "* Getting elixir_sense (https://github.com/elixir-lsp/elixir_sense.git - 5965af7e7a1b743f0c2c475fa2215ec2b23f70c5)\n"
helix_lsp::transport [ERROR] elixir-ls err <- "* Getting erl2ex_vendored (https://github.com/elixir-lsp/erl2ex.git - 073ac6b9a44282e718b6050c7b27cedf9217a12a)\n"
helix_lsp::transport [ERROR] elixir-ls err <- "* Getting dialyxir_vendored (https://github.com/elixir-lsp/dialyxir.git - f8f64cfb6797c518294687e7c03ae817bacbc6ee)\n"
helix_lsp::transport [ERROR] elixir-ls err <- "* Getting jason_v (https://github.com/elixir-lsp/jason.git - f1c10fa9c445cb9f300266122ef18671054b2330)\n"
helix_lsp::transport [ERROR] elixir-ls err <- "* Getting path_glob_vendored (https://github.com/elixir-lsp/path_glob.git - 965350dc41def7be4a70a23904195c733a2ecc84)\n"
helix_lsp::transport [ERROR] elixir-ls err <- "* Getting erlex_vendored (https://github.com/elixir-lsp/erlex.git - c0e448db27bcbb3f369861d13e3b0607ed37048d)\n"

[josevalim]

I asked Claude why longpaths is not the default and it had this to say:

• Windows ecosystem limitations - Even though Windows 10+ supports long paths, many applications, scripts, and tools in the Windows ecosystem still can't handle paths longer than 260 characters. This includes some older versions of Windows Explorer, command prompt tools, and third-party software.
• System-level requirement - Long path support requires both Git configuration AND Windows system-level configuration. Since Git can't guarantee the system is properly configured, enabling it by default could lead to inconsistent behavior.
• Potential for user confusion - If long paths were enabled by default but the user's system or other tools couldn't handle them, it could create confusing error scenarios where Git operations succeed but other operations fail.
• Historical Windows API limitations - The 260-character limit (MAX_PATH) was deeply embedded in Windows APIs for decades. While newer APIs support longer paths, the transition has been gradual, and Git errs on the side of compatibility.

We could try setting it by default within the git dependencies we clone but I am unsure if it would cause other issues. I am also not sure how common this actually is as it is allegedly fixed in more recent Windows versions. At least I will change Elixir to generate slightly shorter paths for installs and ElixirLS should probably do the same.

[wheredoipressnow]

Thank you. Can you please try this in IEx using v1.18.4:

iex> Mix.install [{:elixir_ls, github: "elixir-lsp/elixir-ls", tag: "v0.28.0"}]

Also please try this in your terminal:

$ git clone https://github.com/elixir-lsp/elixir-ls.git
$ cd elixir-ls
$ git checkout --force --quiet v0.28.0

If it fails with the --force flag, please also try it without the --force flag.

@lukaszsamson, here is the Mix diff between Elixir versions. It all points out to the --force flag that we added However, note the error is fully coming from git and it complains about a long filename. According to the docs, Git supports filenames only up to 260 characters, and that particular file is already taking 128 characters. I don't know if the --force flag makes Git behave slightly differently (perhaps it clones it to another directory first, making it go above the file limit). As you know, the --force flag is important to fix the checkout issues, so it is not something we can remove either.

---

On a Windows 11 machine without Git long name support enabled:

Erlang/OTP 27 [erts-15.2.7] [source] [64-bit] [smp:16:16] [ds:16:16:10] [async-threads:1] [jit:ns]

Interactive Elixir (1.18.4) - press Ctrl+C to exit (type h() ENTER for help)
iex(1)> Mix.install [{:elixir_ls, github: "elixir-lsp/elixir-ls", tag: "v0.28.0"}]
* Getting elixir_ls (https://github.com/elixir-lsp/elixir-ls.git - v0.28.0)
remote: Enumerating objects: 16236, done.
remote: Counting objects: 100% (3333/3333), done.
remote: Compressing objects: 100% (819/819), done.
remote: Total 16236 (delta 2874), reused 2522 (delta 2509), pack-reused 12903 (from 2)
* Getting elixir_sense (https://github.com/elixir-lsp/elixir_sense.git - 5965af7e7a1b743f0c2c475fa2215ec2b23f70c5)
remote: Enumerating objects: 16660, done.
remote: Counting objects: 100% (2870/2870), done.
remote: Compressing objects: 100% (684/684), done.
remote: Total 16660 (delta 2341), reused 2356 (delta 2174), pack-reused 13790 (from 2)
* Getting erl2ex_vendored (https://github.com/elixir-lsp/erl2ex.git - 073ac6b9a44282e718b6050c7b27cedf9217a12a)
remote: Enumerating objects: 1496, done.
remote: Counting objects: 100% (65/65), done.
remote: Compressing objects: 100% (56/56), done.
remote: Total 1496 (delta 12), reused 24 (delta 6), pack-reused 1431 (from 1)
* Getting dialyxir_vendored (https://github.com/elixir-lsp/dialyxir.git - f8f64cfb6797c518294687e7c03ae817bacbc6ee)
remote: Enumerating objects: 3682, done.
remote: Counting objects: 100% (146/146), done.
remote: Compressing objects: 100% (80/80), done.
remote: Total 3682 (delta 76), reused 90 (delta 62), pack-reused 3536 (from 3)
* Getting jason_v (https://github.com/elixir-lsp/jason.git - f1c10fa9c445cb9f300266122ef18671054b2330)
remote: Enumerating objects: 1704, done.
remote: Counting objects: 100% (292/292), done.
remote: Compressing objects: 100% (113/113), done.
remote: Total 1704 (delta 222), reused 179 (delta 179), pack-reused 1412 (from 2)
* Getting path_glob_vendored (https://github.com/elixir-lsp/path_glob.git - 965350dc41def7be4a70a23904195c733a2ecc84)
remote: Enumerating objects: 395, done.
remote: Counting objects: 100% (395/395), done.
remote: Compressing objects: 100% (200/200), done.
remote: Total 395 (delta 179), reused 361 (delta 149), pack-reused 0 (from 0)
* Getting erlex_vendored (https://github.com/elixir-lsp/erlex.git - c0e448db27bcbb3f369861d13e3b0607ed37048d)
remote: Enumerating objects: 594, done.
remote: Counting objects: 100% (99/99), done.
remote: Compressing objects: 100% (39/39), done.
remote: Total 594 (delta 68), reused 78 (delta 58), pack-reused 495 (from 1)
Resolving Hex dependencies...
Resolution completed in 0.079s

git clone https://github.com/elixir-lsp/elixir-ls.git

Cloning into 'elixir-ls'...
remote: Enumerating objects: 18132, done.
remote: Counting objects: 100% (3405/3405), done.
remote: Compressing objects: 100% (814/814), done.
remote: Total 18132 (delta 2936), reused 2613 (delta 2575), pack-reused 14727 (from 2)
Receiving objects: 100% (18132/18132), 7.97 MiB | 5.00 MiB/s, done.
Resolving deltas: 100% (11793/11793), done.

Edit:

On a second Windows 11 machine there are no Git requests logged at all. Both times new projects.

Erlang/OTP 27 [erts-15.2.7] [source] [64-bit] [smp:16:16] [ds:16:16:10] [async-threads:1] [jit:ns]

Interactive Elixir (1.18.4) - press Ctrl+C to exit (type h() ENTER for help)
iex(1)> Mix.install [{:elixir_ls, github: "elixir-lsp/elixir-ls", tag: "v0.28.0"}]
==> jason_v
Compiling 10 files (.ex)
Generated jason_v app
==> nimble_parsec
Compiling 4 files (.ex)
warning: _.._ inside match is deprecated, you must always match on the step: _.._//var or _.._//_ if you want to ignore it
  lib/nimble_parsec/compiler.ex:864: NimbleParsec.Compiler.newline_allowed?/1

warning: _.._ inside match is deprecated, you must always match on the step: _.._//var or _.._//_ if you want to ignore it
  lib/nimble_parsec/compiler.ex:873: NimbleParsec.Compiler.newline_forbidden?/1

warning: min..max inside match is deprecated, you must always match on the step: min..max//var or min..max//_ if you want to ignore it
  lib/nimble_parsec/compiler.ex:980: NimbleParsec.Compiler.bin_range_to_guard/2

warning: min..max inside match is deprecated, you must always match on the step: min..max//var or min..max//_ if you want to ignore it
  lib/nimble_parsec/compiler.ex:983: NimbleParsec.Compiler.bin_range_to_guard/2

warning: min..min inside match is deprecated, you must always match on the step: min..min//var or min..min//_ if you want to ignore it
...

[josevalim]

@lukaszsamson are you customizing the path Mix.install installs to? Because if the regular version works then something more may be going on.

[lukaszsamson]

No, I don't customize it

[josevalim]

Alright, I believe we have done some changes on our side to reduce the odds of this happening but I also recommend ElixirLS to reduce the size of the fixture name (for example, the umbrella app and inner app names) to decrease the odds of a clone into a long directory name causing issues. Thanks @wheredoipressnow!