unable to run updater on `rustup self update`

バックトレースに示された self-update のエントリポイント rustup::cli::self_update::unix::run_update から開始し、macOS で rustup update を実行して失敗を再現します。報告された toolchain セットアップに対する updater のパス欠落エラーを追跡します。rustup update が unable-to-run-updater エラーなしで完了すれば完了です。

Verification

• I searched for recent similar issues at https://github.com/rust-lang/rustup/issues?q=is%3Aissue and found no duplicates.
• I am on the latest version of Rustup according to https://github.com/rust-lang/rustup/tags and am still able to reproduce my issue.

Problem

I'm trying to update my rustc versions and the following error occurred:

$ rustup update

info: syncing channel updates for 'stable-aarch64-apple-darwin'
info: latest update on 2026-03-26, rust version 1.94.1 (e408947bf 2026-03-25)
info: downloading component 'rustfmt'
info: downloading component 'cargo'
info: downloading component 'rust-std'
info: downloading component 'rustc'
 61.3 MiB /  61.3 MiB (100 %)  40.8 MiB/s in  1s
info: removing previous version of component 'rustfmt'
info: removing previous version of component 'cargo'
info: removing previous version of component 'rust-std'
info: removing previous version of component 'rustc'
info: installing component 'rustfmt'
info: installing component 'cargo'
info: installing component 'rust-std'
info: installing component 'rustc'
 61.3 MiB /  61.3 MiB (100 %)  29.1 MiB/s in  2s
info: syncing channel updates for 'nightly-aarch64-apple-darwin'
info: latest update on 2026-03-26, rust version 1.96.0-nightly (80d0e4be6 2026-03-25)
info: downloading component 'rustc-dev'
 94.6 MiB /  94.6 MiB (100 %)   4.3 MiB/s in 21s
info: downloading component 'rust-std' for 'x86_64-unknown-freebsd'
 27.6 MiB /  27.6 MiB (100 %)   4.2 MiB/s in  6s
info: downloading component 'rustfmt'
info: downloading component 'miri'
info: downloading component 'rust-src'
info: downloading component 'rust-docs'
info: downloading component 'clippy'
info: downloading component 'cargo'
info: downloading component 'rust-std'
info: downloading component 'rustc'
 46.8 MiB /  46.8 MiB (100 %)  39.9 MiB/s in  1s
info: removing previous version of component 'rustc-dev'
info: removing previous version of component 'rust-std' for 'x86_64-unknown-freebsd'
info: removing previous version of component 'rustfmt'
info: removing previous version of component 'miri'
info: removing previous version of component 'rust-src'
info: removing previous version of component 'rust-docs'
info: removing previous version of component 'clippy'
info: removing previous version of component 'cargo'
info: removing previous version of component 'rust-std'
info: removing previous version of component 'rustc'
info: installing component 'rustc-dev'
 94.6 MiB /  94.6 MiB (100 %)  26.6 MiB/s in  4s
info: installing component 'rust-std' for 'x86_64-unknown-freebsd'
 27.6 MiB /  27.6 MiB (100 %)  27.3 MiB/s in  1s
info: installing component 'rustfmt'
info: installing component 'miri'
info: installing component 'rust-src'
info: installing component 'rust-docs'
 21.3 MiB /  21.3 MiB (100 %)   3.4 MiB/s in  4s
info: installing component 'clippy'
info: installing component 'cargo'
info: installing component 'rust-std'
info: installing component 'rustc'
 46.8 MiB /  46.8 MiB (100 %)  28.4 MiB/s in  1s
info: syncing channel updates for '1.61-aarch64-apple-darwin'
info: syncing channel updates for '1.70-aarch64-apple-darwin'
info: syncing channel updates for '1.86-aarch64-apple-darwin'
info: latest update on 2025-04-03, rust version 1.86.0 (05f9846f8 2025-03-31)
info: syncing channel updates for '1.91-aarch64-apple-darwin'
info: syncing channel updates for '1.92-aarch64-apple-darwin'
info: checking for self-update
info: downloading self-update

   stable-aarch64-apple-darwin updated - rustc 1.94.1 (e408947bf 2026-03-25) (from rustc 1.94.0 (4a4ef493e 2026-03-02))
  nightly-aarch64-apple-darwin updated - rustc 1.96.0-nightly (80d0e4be6 2026-03-25) (from rustc 1.96.0-nightly (69370dc4a 2026-03-05))
   1.61-aarch64-apple-darwin unchanged - rustc 1.61.0 (fe5b13d68 2022-05-18)
   1.70-aarch64-apple-darwin unchanged - rustc 1.70.0 (90c541806 2023-05-31)
   1.86-aarch64-apple-darwin unchanged - (error reading rustc version)
   1.91-aarch64-apple-darwin unchanged - rustc 1.91.1 (ed61e7d7e 2025-11-07)
   1.92-aarch64-apple-darwin unchanged - rustc 1.92.0 (ded5c06cf 2025-12-08)

error: unable to run updater

Caused by:
    No such file or directory (os error 2)

Stack backtrace:
   0: std::backtrace::Backtrace::capture
   1: rustup::cli::self_update::unix::run_update
   2: rustup::cli::rustup_mode::update::{{closure}}
   3: rustup::cli::rustup_mode::main::{{closure}}::{{closure}}
   4: rustup_init::run_rustup_inner::{{closure}}::{{closure}}
   5: rustup_init::run_rustup::{{closure}}::{{closure}}
   6: rustup_init::main::{{closure}}
   7: rustup_init::main
   8: std::sys::backtrace::__rust_begin_short_backtrace
   9: _main

Running it again:

info: syncing channel updates for 'stable-aarch64-apple-darwin'
info: syncing channel updates for 'nightly-aarch64-apple-darwin'
info: syncing channel updates for '1.61-aarch64-apple-darwin'
info: syncing channel updates for '1.70-aarch64-apple-darwin'
info: syncing channel updates for '1.86-aarch64-apple-darwin'
info: latest update on 2025-04-03, rust version 1.86.0 (05f9846f8 2025-03-31)
info: syncing channel updates for '1.91-aarch64-apple-darwin'
info: syncing channel updates for '1.92-aarch64-apple-darwin'
info: checking for self-update
info: downloading self-update

   stable-aarch64-apple-darwin unchanged - rustc 1.94.1 (e408947bf 2026-03-25)
  nightly-aarch64-apple-darwin unchanged - rustc 1.96.0-nightly (80d0e4be6 2026-03-25)
     1.61-aarch64-apple-darwin unchanged - rustc 1.61.0 (fe5b13d68 2022-05-18)
     1.70-aarch64-apple-darwin unchanged - rustc 1.70.0 (90c541806 2023-05-31)
     1.86-aarch64-apple-darwin unchanged - (error reading rustc version)
     1.91-aarch64-apple-darwin unchanged - rustc 1.91.1 (ed61e7d7e 2025-11-07)
     1.92-aarch64-apple-darwin unchanged - rustc 1.92.0 (ded5c06cf 2025-12-08)

error: unable to run updater

Caused by:
    No such file or directory (os error 2)

Stack backtrace:
   0: std::backtrace::Backtrace::capture
   1: rustup::cli::self_update::unix::run_update
   2: rustup::cli::rustup_mode::update::{{closure}}
   3: rustup::cli::rustup_mode::main::{{closure}}::{{closure}}
   4: rustup_init::run_rustup_inner::{{closure}}::{{closure}}
   5: rustup_init::run_rustup::{{closure}}::{{closure}}
   6: rustup_init::main::{{closure}}
   7: rustup_init::main
   8: std::sys::backtrace::__rust_begin_short_backtrace
   9: _main

Steps

1. run rustup update.

Possible Solution(s)

No response

Notes

No response

Rustup version

rustup 1.28.2 (e4f3ad6f8 2025-04-28)
info: This is the version for the rustup toolchain manager, not the rustc compiler.
info: The currently active `rustc` version is `rustc 1.96.0-nightly (80d0e4be6 2026-03-25)`

Installed toolchains

Default host: aarch64-apple-darwin
rustup home:  /Users/thomas/.rustup

installed toolchains
--------------------
stable-aarch64-apple-darwin
nightly-aarch64-apple-darwin (active, default)
nightly-2024-06-30-aarch64-apple-darwin
nightly-2025-05-04-aarch64-apple-darwin
1.61-aarch64-apple-darwin
1.70-aarch64-apple-darwin
1.86-aarch64-apple-darwin
1.91-aarch64-apple-darwin
1.92-aarch64-apple-darwin

active toolchain
----------------
name: nightly-aarch64-apple-darwin
active because: it's the default toolchain
installed targets:
  aarch64-apple-darwin
  x86_64-unknown-freebsd

OS version

macOS 15.7.4