title: How can I update the stable toolchain when I get the error "some components unavailable for target i386-apple-ios/armv7s-apple-ios"?
body: <p>I try to run</p>
  
  <pre class="lang-none prettyprint-override"><code>rustup update stable
  </code></pre>
  
  <p>and I get the following output.</p>
  
  <pre class="lang-none prettyprint-override"><code>info: syncing channel updates for 'stable-x86_64-unknown-linux-gnu'
  info: latest update on 2020-05-07, rust version 1.43.1 (8d69840ab 2020-05-04)
  error: some components unavailable for download for channel stable: 'rust-std' for target 'i386-apple-ios', 'rust-std' for target 'armv7s-apple-ios', 'rust-std' for target 'armv7-apple-ios'
  If you require these components, please install and use the latest successful build version,
  which you can find at &lt;https://rust-lang.github.io/rustup-components-history&gt;.
  
  After determining the correct date, install it with a command such as:
  
      rustup toolchain install nightly-2018-12-27
  
  Then you can use the toolchain with commands such as:
  
      cargo +nightly-2018-12-27 build
  </code></pre>
  
  <p>While I can install the latest stable toolchain using</p>
  
  <pre class="lang-none prettyprint-override"><code>rustup toolchain install stable-2020-05-07
  </code></pre>
  
  <p>That creates a separate toolchain.</p>
  
  <pre class="lang-none prettyprint-override"><code>rustup toolchain list
  stable-2020-05-07-x86_64-unknown-linux-gnu (default)
  stable-x86_64-unknown-linux-gnu
  nightly-2020-05-07-x86_64-unknown-linux-gnu
  </code></pre>
  
  <p>I can use this new toolchain as the default (as I am now), but it's going to be a pain moving forward as I can't just use <code>rustup update</code>.</p>
  
  <p>Running <code>rustup toolchain install stable</code> yields the same error.</p>
  
  <p>How can I get the stable Rust toolchain to update via <code>rustup update run</code>?</p>