.

packages/ruby/src/install-ruby.ts

@@ -31,7 +31,7 @@ function getLatestRubyVersion(): RubyVersion {
   const selection = allOptions.find(isInstalled);
   if (!selection) {
     throw new NowBuildError({
-      code: 'RUBY_NOT_FOUND',
+      code: 'RUBY_INVALID_VERSION',
       link: 'http://vercel.link/ruby-version',
       message: `Unable to find any supported Ruby versions.`,
     });
@@ -60,7 +60,7 @@ function getRubyPath(meta: Meta, gemfileContents: string) {
         // The array is already in order so return the first
         // match which will be the newest version.
         selection = o;
-        return intersects(o.range, strVersion) && isInstalled(o);
+        return intersects(o.range, strVersion);
       });
       if (!found) {
         throw new NowBuildError({
@@ -69,12 +69,17 @@ function getRubyPath(meta: Meta, gemfileContents: string) {
           link: 'http://vercel.link/ruby-version',
         });
       }
-      if (isDiscontinued(selection)) {
+      const discontinued = isDiscontinued(selection);
+      if (discontinued || !isInstalled(selection)) {
         const latest = getLatestRubyVersion();
-        const intro = `Found \`Gemfile\` with discontinued Ruby version: \`${line}.\``;
+        const intro = `Found \`Gemfile\` with ${
+          discontinued ? 'discontinued' : 'invalid'
+        } Ruby version: \`${line}.\``;
         const hint = `Please set \`ruby "~> ${latest.range}"\` in your \`Gemfile\` to use Ruby ${latest.range}.`;
         throw new NowBuildError({
-          code: 'RUBY_DISCONTINUED_VERSION',
+          code: discontinued
+            ? 'RUBY_DISCONTINUED_VERSION'
+            : 'RUBY_INVALID_VERSION',
           link: 'http://vercel.link/ruby-version',
           message: `${intro} ${hint}`,
         });

packages/ruby/test/fixtures/12-version-3-3-on-al2-error/Gemfile

@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+source "https://rubygems.org"
+
+ruby "~> 3.3.x"
+
+gem "cowsay", "~> 0.3.0"

packages/ruby/test/fixtures/12-version-3-3-on-al2-error/Gemfile.lock

@@ -0,0 +1,16 @@
+GEM
+  remote: https://rubygems.org/
+  specs:
+    cowsay (0.3.0)
+
+PLATFORMS
+  x86_64-linux
+
+DEPENDENCIES
+  cowsay (~> 0.3.0)
+
+RUBY VERSION
+   ruby 2.5.5p157
+
+BUNDLED WITH
+   2.2.22

packages/ruby/test/fixtures/12-version-3-3-on-al2-error/index.rb

@@ -0,0 +1,9 @@
+require 'cowsay'
+
+Handler = Proc.new do |req, res|
+  name = req.query['name'] || 'World'
+
+  res.status = 200
+  res['Content-Type'] = 'text/text; charset=utf-8'
+  res.body = Cowsay.say("Hello #{name}", 'cow')
+end

packages/ruby/test/fixtures/12-version-3-3-on-al2-error/package.json

@@ -0,0 +1,5 @@
+{
+  "engines": {
+    "node": "18.x"
+  }
+}

packages/ruby/test/fixtures/12-version-3-3-on-al2-error/vercel.json

@@ -0,0 +1,4 @@
+{
+  "version": 2,
+  "builds": [{ "src": "index.rb", "use": "@vercel/ruby" }]
+}