diff --git a/.github/workflows/docker.yml b/.github/workflows/docker.yml
index e77b275902..fd7dc1ded1 100644
--- a/.github/workflows/docker.yml
+++ b/.github/workflows/docker.yml
@@ -18,6 +18,7 @@ defaults:
     shell: bash -xeuo pipefail {0}
 
 env:
+  # odeprecated: remove 18.04 image in Homebrew >=4.5
   VERSIONS: '["18.04", "20.04", "22.04", "24.04"]'
 
 jobs:
@@ -145,9 +146,11 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
+        # odeprecated: remove 18.04 image in Homebrew >=4.5
         version: ["18.04", "20.04", "22.04", "24.04"]
         arch: ["x86_64", "arm64"]
         exclude:
+          # odeprecated: move this to 20.04 in Homebrew >=4.5 and remove 18.04 image
           - version: "18.04"
             arch: "arm64"
           - arch: ${{ github.event_name == 'release' && 'arm64' }}
@@ -172,9 +175,9 @@ jobs:
           VERSION: ${{ matrix.version }}
           PUSH: ${{ needs.generate-tags.outputs.push }}
         run: |
+          # odeprecated: move this to 20.04 in Homebrew >=4.5 and remove 18.04 image
           if [[ "${VERSION}" == "18.04" ]]; then
-            # odeprecated: remove this in Homebrew >=4.5
-            echo "The homebrew/ubuntu18.04 image is deprecated and will soon be retired. Use homebrew/ubuntu22.04 or homebrew/ubuntu24.04 or homebrew/ubuntu20.04 or homebrew/brew." > .docker-deprecate
+            echo "The homebrew/ubuntu18.04 image is deprecated and will soon be retired. Use homebrew/ubuntu22.04 or homebrew/ubuntu24.04 or homebrew/brew." > .docker-deprecate
           fi
 
           filter="$(printf '.["%s"]' "${VERSION}")"
@@ -197,10 +200,22 @@ jobs:
           build-args: version=${{ matrix.version }}
           labels: ${{ needs.generate-tags.outputs.labels }}
 
-      - name: Run brew test-bot --only-setup
-        run: docker run --env HOMEBREW_ARM64_TESTING --rm brew brew test-bot --only-setup
+      - name: Set environment variables
+        run: |
+          if [[ "${ARCH}" == "arm64" ]]; then
+            echo "HOMEBREW_ARM64_TESTING=1" >> "$GITHUB_ENV"
+          fi
+
+          # odeprecated: remove 18.04 in Homebrew >=4.5
+          if [[ "${VERSION}" == "18.04" || "${VERSION}" == "20.04" ]]; then
+            echo "HOMEBREW_GLIBC_TESTING=1" >> "$GITHUB_ENV"
+          fi
         env:
-          HOMEBREW_ARM64_TESTING: 1
+          VERSION: ${{ matrix.version }}
+          ARCH: ${{ matrix.arch }}
+
+      - name: Run brew test-bot --only-setup
+        run: docker run --env HOMEBREW_ARM64_TESTING --env HOMEBREW_GLIBC_TESTING --rm brew brew test-bot --only-setup
 
       - name: Log in to GitHub Packages (BrewTestBot)
         if: fromJSON(steps.attributes.outputs.push)
@@ -286,6 +301,7 @@ jobs:
           done <<<"$(jq --raw-output "${filter}" <<<"${TAGS}")"
 
           image_args=("ghcr.io/homebrew/ubuntu${VERSION}@sha256:$(<"${RUNNER_TEMP}/digests/${VERSION}-x86_64")")
+          # odeprecated: move this to 20.04 in Homebrew >=4.5 and remove 18.04 image
           if [[ "${VERSION}" != 18.04 ]]; then
             image_args+=("ghcr.io/homebrew/ubuntu${VERSION}@sha256:$(<"${RUNNER_TEMP}/digests/${VERSION}-arm64")")
           fi
diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 2ca5d2e40e..760959cb28 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -388,6 +388,10 @@ jobs:
 
       - run: brew test-bot --only-cleanup-before
 
+      - name: Setup environment variables
+        if: matrix.container == 'ghcr.io/homebrew/ubuntu20.04:latest'
+        run: echo "HOMEBREW_GLIBC_TESTING=1" >> "$GITHUB_ENV"
+
       - run: brew test-bot --only-setup
 
       - run: brew install gnu-tar
diff --git a/Library/Homebrew/attestation.rb b/Library/Homebrew/attestation.rb
index 00efbcad29..44f1a4d0b3 100644
--- a/Library/Homebrew/attestation.rb
+++ b/Library/Homebrew/attestation.rb
@@ -66,7 +66,7 @@ module Homebrew
       return false if Homebrew::EnvConfig.no_verify_attestations?
       return true if Homebrew::EnvConfig.verify_attestations?
       return false if ENV.fetch("CI", false)
-      return false if OS.unsupported_configuration?
+      return false if OS.not_tier_one_configuration?
 
       # Always check credentials last to avoid unnecessary credential extraction.
       (Homebrew::EnvConfig.developer? || Homebrew::EnvConfig.devcmdrun?) && GitHub::API.credentials.present?
diff --git a/Library/Homebrew/brew.rb b/Library/Homebrew/brew.rb
index ced88c58be..478517b1be 100644
--- a/Library/Homebrew/brew.rb
+++ b/Library/Homebrew/brew.rb
@@ -169,8 +169,13 @@ rescue BuildError => e
   Utils::Analytics.report_build_error(e)
   e.dump(verbose: args&.verbose? || false)
 
-  if OS.unsupported_configuration?
-    $stderr.puts "#{Tty.bold}Do not report this issue: you are running in an unsupported configuration.#{Tty.reset}"
+  if OS.not_tier_one_configuration?
+    $stderr.puts <<~EOS
+      This build failure was expected, as this is not a Tier 1 configuration:
+        #{Formatter.url("https://docs.brew.sh/Support-Tiers")}
+      #{Formatter.bold("Do not report any issues to Homebrew/* repositories!")}
+      Read the above document instead before opening any issues or PRs.
+    EOS
   elsif e.formula.head? || e.formula.deprecated? || e.formula.disabled?
     reason = if e.formula.head?
       "was built from an unstable upstream --HEAD"
@@ -182,14 +187,7 @@ rescue BuildError => e
     $stderr.puts <<~EOS
       #{e.formula.name}'s formula #{reason}.
       This build failure is expected behaviour.
-      Do not create issues about this on Homebrew's GitHub repositories.
-      Any opened issues will be immediately closed without response.
-      Do not ask for help from Homebrew or its maintainers on social media.
-      You may ask for help in Homebrew's discussions but are unlikely to receive a response.
-      Try to figure out the problem yourself and submit a fix as a pull request.
-      We will review it but may or may not accept it.
     EOS
-
   end
 
   exit 1
@@ -211,15 +209,20 @@ rescue Exception => e # rubocop:disable Lint/RescueException
   require "utils/backtrace"
   $stderr.puts Utils::Backtrace.clean(e) if args&.debug? || ARGV.include?("--debug") || !method_deprecated_error
 
-  if OS.unsupported_configuration?
-    $stderr.puts "#{Tty.bold}Do not report this issue: you are running in an unsupported configuration.#{Tty.reset}"
+  if OS.not_tier_one_configuration?
+    $stderr.puts <<~EOS
+      This error was expected, as this is not a Tier 1 configuration:
+        #{Formatter.url("https://docs.brew.sh/Support-Tiers")}
+      #{Formatter.bold("Do not report any issues to Homebrew/* repositories!")}
+      Read the above document instead before opening any issues or PRs.
+    EOS
   elsif Homebrew::EnvConfig.no_auto_update? &&
         (fetch_head = HOMEBREW_REPOSITORY/".git/FETCH_HEAD") &&
         (!fetch_head.exist? || (fetch_head.mtime.to_date < Date.today))
     $stderr.puts "#{Tty.bold}You have disabled automatic updates and have not updated today.#{Tty.reset}"
     $stderr.puts "#{Tty.bold}Do not report this issue until you've run `brew update` and tried again.#{Tty.reset}"
   elsif (issues_url = (method_deprecated_error && e.issues_url) || Utils::Backtrace.tap_error_url(e))
-    $stderr.puts "If reporting this issue please do so at (not Homebrew/brew or Homebrew/homebrew-core):"
+    $stderr.puts "If reporting this issue please do so at (not Homebrew/* repositories):"
     $stderr.puts "  #{Formatter.url(issues_url)}"
   elsif internal_cmd
     $stderr.puts "#{Tty.bold}Please report this issue:#{Tty.reset}"
diff --git a/Library/Homebrew/diagnostic.rb b/Library/Homebrew/diagnostic.rb
index 71d7f95ddf..80921c4cc6 100644
--- a/Library/Homebrew/diagnostic.rb
+++ b/Library/Homebrew/diagnostic.rb
@@ -111,17 +111,21 @@ module Homebrew
         supported_configuration_checks + build_from_source_checks
       end
 
-      def please_create_pull_requests(what = "unsupported configuration")
+      sig { params(tier: T.any(Integer, String, Symbol)).returns(T.nilable(String)) }
+      def support_tier_message(tier:)
+        return if tier.to_s == "1"
+
+        tier_title, tier_slug = if tier.to_s == "unsupported"
+          ["Unsupported", "unsupported"]
+        else
+          ["Tier #{tier}", "tier-#{tier.to_s.downcase}"]
+        end
+
         <<~EOS
-          It is expected behaviour that some formulae will fail to build in this #{what}.
-          It is expected behaviour that Homebrew will be buggy and slow.
-          Do not create any issues about this on Homebrew's GitHub repositories.
-          Do not create any issues even if you think this message is unrelated.
-          Any opened issues will be immediately closed without response.
-          Do not ask for help from Homebrew or its maintainers on social media.
-          You may ask for help in Homebrew's discussions but are unlikely to receive a response.
-          Try to figure out the problem yourself and submit a fix as a pull request.
-          We will review it but may or may not accept it.
+          This is a #{tier_title} configuration:
+            #{Formatter.url("https://docs.brew.sh/Support-Tiers##{tier_slug}")}
+          #{Formatter.bold("Do not report any issues to Homebrew/* repositories!")}
+          Read the above document instead before opening any issues or PRs.
         EOS
       end
 
@@ -834,9 +838,10 @@ module Homebrew
         <<~EOS
           Your Homebrew's prefix is not #{Homebrew::DEFAULT_PREFIX}.
 
-          Many of Homebrew's bottles (binary packages) can only be used with the default prefix.
+          Most of Homebrew's bottles (binary packages) can only be used with the default prefix.
           Consider uninstalling Homebrew and reinstalling into the default prefix.
-          #{please_create_pull_requests}
+
+          #{support_tier_message(tier: 3)}
         EOS
       end
 
diff --git a/Library/Homebrew/exceptions.rb b/Library/Homebrew/exceptions.rb
index c03f9569e9..3ca5ce90ff 100644
--- a/Library/Homebrew/exceptions.rb
+++ b/Library/Homebrew/exceptions.rb
@@ -521,23 +521,31 @@ class BuildError < RuntimeError
       end
     end
 
-    if formula.tap && !OS.unsupported_configuration?
-      if formula.tap.official?
+    if formula.tap
+      if OS.not_tier_one_configuration?
+        <<~EOS
+          This is not a Tier 1 configuration:
+            #{Formatter.url("https://docs.brew.sh/Support-Tiers")}
+          #{Formatter.bold("Do not report any issues to Homebrew/* repositories!")}
+          Read the above document instead before opening any issues or PRs.
+        EOS
+      elsif formula.tap.official?
         puts Formatter.error(Formatter.url(OS::ISSUES_URL), label: "READ THIS")
       elsif (issues_url = formula.tap.issues_url)
         puts <<~EOS
-          If reporting this issue please do so at (not Homebrew/brew or Homebrew/homebrew-core):
+          If reporting this issue please do so at (not Homebrew/* repositories):
             #{Formatter.url(issues_url)}
         EOS
       else
         puts <<~EOS
-          If reporting this issue please do so to (not Homebrew/brew or Homebrew/homebrew-core):
+          If reporting this issue please do so to (not Homebrew/* repositories):
             #{formula.tap}
         EOS
       end
     else
-      puts <<~EOS
-        Do not report this issue to Homebrew/brew or Homebrew/homebrew-core!
+      <<~EOS
+        We cannot detect the correct tap to report this issue to.
+        Do not report this issue to Homebrew/* repositories!
       EOS
     end
 
diff --git a/Library/Homebrew/extend/kernel.rb b/Library/Homebrew/extend/kernel.rb
index e92210b18d..56eb04b97d 100644
--- a/Library/Homebrew/extend/kernel.rb
+++ b/Library/Homebrew/extend/kernel.rb
@@ -171,7 +171,7 @@ module Kernel
 
       tap = Tap.fetch(match[:user], match[:repository])
       tap_message = "\nPlease report this issue to the #{tap.full_name} tap"
-      tap_message += " (not Homebrew/brew or Homebrew/homebrew-core)" unless tap.official?
+      tap_message += " (not Homebrew/* repositories)" unless tap.official?
       tap_message += ", or even better, submit a PR to fix it" if replacement
       tap_message << ":\n  #{line.sub(/^(.*:\d+):.*$/, '\1')}\n\n"
       break
diff --git a/Library/Homebrew/extend/os/linux/diagnostic.rb b/Library/Homebrew/extend/os/linux/diagnostic.rb
index b3d0e5a510..034d047961 100644
--- a/Library/Homebrew/extend/os/linux/diagnostic.rb
+++ b/Library/Homebrew/extend/os/linux/diagnostic.rb
@@ -80,7 +80,8 @@ module OS
           <<~EOS
             Your CPU architecture (#{Hardware::CPU.arch}) is not supported. We only support
             x86_64 CPU architectures. You will be unable to use binary packages (bottles).
-            #{please_create_pull_requests}
+
+            #{support_tier_message(tier: 2)}
           EOS
         end
 
@@ -90,10 +91,30 @@ module OS
           <<~EOS
             Your system glibc #{OS::Linux::Glibc.system_version} is too old.
             We only support glibc #{OS::Linux::Glibc.minimum_version} or later.
-            #{please_create_pull_requests}
+
             We recommend updating to a newer version via your distribution's
             package manager, upgrading your distribution to the latest version,
             or changing distributions.
+
+            #{support_tier_message(tier: :unsupported)}
+          EOS
+        end
+
+        def check_glibc_version
+          return unless OS::Linux::Glibc.below_ci_version?
+
+          # We want to bypass this check in some tests.
+          return if ENV["HOMEBREW_GLIBC_TESTING"]
+
+          <<~EOS
+            Your system glibc #{OS::Linux::Glibc.system_version} is too old.
+            We will need to automatically install a newer version.
+
+            We recommend updating to a newer version via your distribution's
+            package manager, upgrading your distribution to the latest version,
+            or changing distributions.
+
+            #{support_tier_message(tier: 2)}
           EOS
         end
 
@@ -104,10 +125,12 @@ module OS
             Your Linux kernel #{OS.kernel_version} is too old.
             We only support kernel #{OS::Linux::Kernel.minimum_version} or later.
             You will be unable to use binary packages (bottles).
-            #{please_create_pull_requests}
+
             We recommend updating to a newer version via your distribution's
             package manager, upgrading your distribution to the latest version,
             or changing distributions.
+
+            #{support_tier_message(tier: 3)}
           EOS
         end
 
diff --git a/Library/Homebrew/extend/os/mac/diagnostic.rb b/Library/Homebrew/extend/os/mac/diagnostic.rb
index 6f11864cad..e3082cea16 100644
--- a/Library/Homebrew/extend/os/mac/diagnostic.rb
+++ b/Library/Homebrew/extend/os/mac/diagnostic.rb
@@ -110,10 +110,12 @@ module OS
           return if Homebrew::EnvConfig.developer?
           return if ENV["HOMEBREW_INTEGRATION_TEST"]
 
+          tier = 2
           who = +"We"
           what = if OS::Mac.version.prerelease?
             "pre-release version"
           elsif OS::Mac.version.outdated_release?
+            tier = 3
             who << " (and Apple)"
             "old version"
           end
@@ -124,7 +126,8 @@ module OS
           <<~EOS
             You are using macOS #{MacOS.version}.
             #{who} do not provide support for this #{what}.
-            #{please_create_pull_requests(what)}
+
+            #{support_tier_message(tier:)}
           EOS
         end
 
@@ -145,7 +148,8 @@ module OS
           <<~EOS
             You have booted macOS using OpenCore Legacy Patcher.
             We do not provide support for this configuration.
-            #{please_create_pull_requests}
+
+            #{support_tier_message(tier: 2)}
           EOS
         end
 
@@ -169,6 +173,8 @@ module OS
             Your Xcode (#{MacOS::Xcode.version}) is outdated.
             Please update to Xcode #{MacOS::Xcode.latest_version} (or delete it).
             #{MacOS::Xcode.update_instructions}
+
+            #{support_tier_message(tier: 2)}
           EOS
 
           if OS::Mac.version.prerelease?
@@ -198,6 +204,8 @@ module OS
           <<~EOS
             A newer Command Line Tools release is available.
             #{MacOS::CLT.update_instructions}
+
+            #{support_tier_message(tier: 2)}
           EOS
         end
 
@@ -409,6 +417,8 @@ module OS
 
             You should set the "HOMEBREW_TEMP" environment variable to a suitable
             directory on the same volume as your Cellar.
+
+            #{support_tier_message(tier: 2)}
           EOS
         end
 
diff --git a/Library/Homebrew/formula_installer.rb b/Library/Homebrew/formula_installer.rb
index e84bea4082..9cec5cee4c 100644
--- a/Library/Homebrew/formula_installer.rb
+++ b/Library/Homebrew/formula_installer.rb
@@ -378,15 +378,10 @@ class FormulaInstaller
           If you're feeling brave, you can try to install from source with:
             brew install --build-from-source #{formula}
 
-          It is expected behaviour that most formulae will fail to build from source.
-          It is expected behaviour that Homebrew will be buggy and slow when building from source.
-          Do not create any issues about failures building from source on Homebrew's GitHub repositories.
-          Do not create any issues building from source even if you think this message is unrelated.
-          Any opened issues will be immediately closed without response.
-          Do not ask for help from Homebrew or its maintainers on social media.
-          You may ask for help building from source in Homebrew's discussions but are unlikely to receive a response.
-          If building from source fails, try to figure out the problem yourself and submit a fix as a pull request.
-          We will review it but may or may not accept it.
+          This is a Tier 3 configuration:
+            #{Formatter.url("https://docs.brew.sh/Support-Tiers#tier-3")}
+          #{Formatter.bold("Do not report any issues to Homebrew/* repositories!")}
+          Read the above document instead before opening any issues or PRs.
         EOS
         raise CannotInstallFormulaError, message
       end
@@ -608,7 +603,7 @@ on_request: installed_on_request?, options:)
       raise if Homebrew::EnvConfig.developer?
 
       $stderr.puts "Please report this issue to the #{formula.tap&.full_name} tap".squeeze(" ")
-      $stderr.puts " (not Homebrew/brew or Homebrew/homebrew-core)!" unless formula.core_formula?
+      $stderr.puts " (not Homebrew/* repositories)!" unless formula.core_formula?
       false
     else
       f.linked_keg.exist? && f.opt_prefix.exist?
diff --git a/Library/Homebrew/install.rb b/Library/Homebrew/install.rb
index 140f7953cd..f001f41578 100644
--- a/Library/Homebrew/install.rb
+++ b/Library/Homebrew/install.rb
@@ -26,7 +26,8 @@ module Homebrew
         @checks ||= Diagnostic::Checks.new
         opoo <<~EOS
           You passed `--cc=#{cc}`.
-          #{@checks.please_create_pull_requests}
+
+          #{@checks.support_tier_message(tier: 3)}
         EOS
       end
 
diff --git a/Library/Homebrew/os.rb b/Library/Homebrew/os.rb
index 30fe342779..3cd2b7f6f1 100644
--- a/Library/Homebrew/os.rb
+++ b/Library/Homebrew/os.rb
@@ -56,7 +56,7 @@ module OS
   if OS.mac?
     require "os/mac"
     require "hardware"
-    # Don't tell people to report issues on unsupported configurations.
+    # Don't tell people to report issues on non-Tier 1 configurations.
     if !OS::Mac.version.prerelease? &&
        !OS::Mac.version.outdated_release? &&
        ARGV.none? { |v| v.start_with?("--cc=") } &&
@@ -76,7 +76,7 @@ module OS
   end
 
   sig { returns(T::Boolean) }
-  def self.unsupported_configuration?
+  def self.not_tier_one_configuration?
     !defined?(OS::ISSUES_URL)
   end
 end
diff --git a/Library/Homebrew/utils/formatter.rb b/Library/Homebrew/utils/formatter.rb
index 245dd71656..9815425204 100644
--- a/Library/Homebrew/utils/formatter.rb
+++ b/Library/Homebrew/utils/formatter.rb
@@ -25,10 +25,14 @@ module Formatter
     "#{Tty.green}#{string}#{Tty.default}"
   end
 
-  def self.option(string)
+  def self.bold(string)
     "#{Tty.bold}#{string}#{Tty.reset}"
   end
 
+  def self.option(string)
+    bold(string)
+  end
+
   # Format a string as success, with an optional label.
   #
   # @api internal