diff --git a/.github/workflows/ci_cd.yml b/.github/workflows/ci_cd.yml
index ef42ab09..579f7f4f 100644
--- a/.github/workflows/ci_cd.yml
+++ b/.github/workflows/ci_cd.yml
@@ -34,7 +34,7 @@ jobs:
       # Specify the OTP and Elixir versions to use when building
       # and running the workflow steps.
       matrix:
-        otp: [ '27.2.1' ]              # Define the OTP version [required]
+        otp: [ '27.3.4.13' ]           # Define the OTP version [required]
         elixir: [ '1.18.2-otp-27' ]    # Define the elixir version [required]
     steps:
       # Step: Check out the code.
@@ -86,7 +86,7 @@ jobs:
       # Specify the OTP and Elixir versions to use when building
       # and running the workflow steps.
       matrix:
-        otp: [ '27.2.1' ]              # Define the OTP version [required]
+        otp: [ '27.3.4.13' ]           # Define the OTP version [required]
         elixir: [ '1.18.2-otp-27' ]    # Define the elixir version [required]
     steps:
       # Step: Check out the code.
diff --git a/.tool-versions b/.tool-versions
index e4c737a8..793176ef 100644
--- a/.tool-versions
+++ b/.tool-versions
@@ -1,2 +1,2 @@
 elixir 1.18.2-otp-27
-erlang 27.2.1
+erlang 27.3.4.13
diff --git a/Dockerfile b/Dockerfile
index aae07479..350ce41e 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -12,8 +12,8 @@
 #   - Ex: hexpm/elixir:1.14.3-erlang-24.3.4.10-debian-bullseye-20230227-slim
 #
 ARG ELIXIR_VERSION=1.18.2
-ARG OTP_VERSION=27.2.1
-ARG DEBIAN_VERSION=bookworm-20250113-slim
+ARG OTP_VERSION=27.3.4.13
+ARG DEBIAN_VERSION=bookworm-20260518-slim
 
 ARG BUILDER_IMAGE="hexpm/elixir:${ELIXIR_VERSION}-erlang-${OTP_VERSION}-debian-${DEBIAN_VERSION}"
 ARG RUNNER_IMAGE="debian:${DEBIAN_VERSION}"
diff --git a/config/runtime.exs b/config/runtime.exs
index dd0970a2..34d4255c 100644
--- a/config/runtime.exs
+++ b/config/runtime.exs
@@ -131,9 +131,24 @@ if System.get_env("PHX_SERVER") do
   config :pears, PearsWeb.Endpoint, server: true
 end
 
-config :pears, slack_client_id: System.fetch_env!("SLACK_CLIENT_ID")
-config :pears, slack_client_secret: System.fetch_env!("SLACK_CLIENT_SECRET")
-config :pears, slack_signing_secret: System.fetch_env!("SLACK_SIGNING_SECRET")
+# Slack credentials are required in production (fail fast if missing), but in
+# dev/test we fall back to placeholders so the app can boot without the secrets
+# being present (e.g. in CI). Tests sign requests with whatever is configured
+# here, so a fixed placeholder is sufficient.
+if config_env() == :prod do
+  config :pears, slack_client_id: System.fetch_env!("SLACK_CLIENT_ID")
+  config :pears, slack_client_secret: System.fetch_env!("SLACK_CLIENT_SECRET")
+  config :pears, slack_signing_secret: System.fetch_env!("SLACK_SIGNING_SECRET")
+else
+  config :pears, slack_client_id: System.get_env("SLACK_CLIENT_ID", "test-slack-client-id")
+
+  config :pears,
+    slack_client_secret: System.get_env("SLACK_CLIENT_SECRET", "test-slack-client-secret")
+
+  config :pears,
+    slack_signing_secret: System.get_env("SLACK_SIGNING_SECRET", "test-slack-signing-secret")
+end
+
 config :pears, slack_oauth_redirect_uri: System.get_env("SLACK_OAUTH_URL")
 
 case System.fetch_env("OTEL_EXPORTER") do
diff --git a/lib/pears/slack.ex b/lib/pears/slack.ex
index ce7a92c5..5ee5e695 100644
--- a/lib/pears/slack.ex
+++ b/lib/pears/slack.ex
@@ -216,6 +216,13 @@ defmodule Pears.Slack do
         O11y.set_error(error)
         {:error, error}
     end
+  rescue
+    # The Slack HTTP client raises on transport-level failures (e.g. a TLS
+    # handshake alert). Capture it as an error rather than letting it crash the
+    # caller (which previously took down the record-pears LiveView handler).
+    exception ->
+      O11y.set_error(exception)
+      {:error, exception}
   end
 
   defp fetch_tokens(slack_code) do
diff --git a/lib/pears_web/live/pairing_board_live.ex b/lib/pears_web/live/pairing_board_live.ex
index e4d65129..4628f105 100644
--- a/lib/pears_web/live/pairing_board_live.ex
+++ b/lib/pears_web/live/pairing_board_live.ex
@@ -108,12 +108,12 @@ defmodule PearsWeb.PairingBoardLive do
 
     case Pears.record_pears(team_name) do
       {:ok, _updated_team} ->
-        Slack.send_daily_pears_summary(team_name)
+        # Post the Slack summary off the reply path so a slow or failing Slack
+        # call can't block the response or crash this handler. The board itself
+        # refreshes via the PubSub team-updated broadcast that record_pears fires.
+        send(self(), {:post_daily_pears_summary, team_name})
 
-        {:noreply,
-         socket
-         |> put_flash(:info, "Today's assigned pears have been recorded!")
-         |> push_navigate(to: "/")}
+        {:noreply, put_flash(socket, :info, "Today's assigned pears have been recorded!")}
 
       {:error, changeset} ->
         Pears.O11y.set_changeset_errors(changeset)
@@ -125,6 +125,7 @@ defmodule PearsWeb.PairingBoardLive do
 
       error ->
         O11y.set_error(error)
+        {:noreply, put_flash(socket, :error, "Sorry! Something went wrong, please try again.")}
     end
   end
 
@@ -277,6 +278,22 @@ defmodule PearsWeb.PairingBoardLive do
     {:noreply, put_flash(socket, type, message)}
   end
 
+  @impl true
+  def handle_info({:post_daily_pears_summary, team_name}, socket) do
+    case Slack.send_daily_pears_summary(team_name) do
+      {:error, _reason} ->
+        {:noreply,
+         put_flash(
+           socket,
+           :error,
+           "Today's pears were recorded, but the Slack summary could not be posted."
+         )}
+
+      _ ->
+        {:noreply, socket}
+    end
+  end
+
   defp team(socket), do: socket.assigns.team
   defp team_name(socket), do: team(socket).name
   defp selected_pear(socket), do: socket.assigns.selected_pear
diff --git a/mix.lock b/mix.lock
index bb52ebec..3fe622b3 100644
--- a/mix.lock
+++ b/mix.lock
@@ -3,7 +3,6 @@
   "bandit": {:hex, :bandit, "1.10.2", "d15ea32eb853b5b42b965b24221eb045462b2ba9aff9a0bda71157c06338cbff", [:mix], [{:hpax, "~> 1.0", [hex: :hpax, repo: "hexpm", optional: false]}, {:plug, "~> 1.18", [hex: :plug, repo: "hexpm", optional: false]}, {:telemetry, "~> 0.4 or ~> 1.0", [hex: :telemetry, repo: "hexpm", optional: false]}, {:thousand_island, "~> 1.0", [hex: :thousand_island, repo: "hexpm", optional: false]}, {:websock, "~> 0.5", [hex: :websock, repo: "hexpm", optional: false]}], "hexpm", "27b2a61b647914b1726c2ced3601473be5f7aa6bb468564a688646a689b3ee45"},
   "bcrypt_elixir": {:hex, :bcrypt_elixir, "3.2.1", "e361261a0401d82dadc1ab7b969f91d250bf7577283e933fe8c5b72f8f5b3c46", [:make, :mix], [{:comeonin, "~> 5.3", [hex: :comeonin, repo: "hexpm", optional: false]}, {:elixir_make, "~> 0.6", [hex: :elixir_make, repo: "hexpm", optional: false]}], "hexpm", "81170177d5c2e280d12141a0b9d9e299bf731535e2d959982bdcd4cfe3c82865"},
   "bunt": {:hex, :bunt, "1.0.0", "081c2c665f086849e6d57900292b3a161727ab40431219529f13c4ddcf3e7a44", [:mix], [], "hexpm", "dc5f86aa08a5f6fa6b8096f0735c4e76d54ae5c9fa2c143e5a1fc7c1cd9bb6b5"},
-  "castore": {:hex, :castore, "1.0.12", "053f0e32700cbec356280c0e835df425a3be4bc1e0627b714330ad9d0f05497f", [:mix], [], "hexpm", "3dca286b2186055ba0c9449b4e95b97bf1b57b47c1f2644555879e659960c224"},
   "cc_precompiler": {:hex, :cc_precompiler, "0.1.11", "8c844d0b9fb98a3edea067f94f616b3f6b29b959b6b3bf25fee94ffe34364768", [:mix], [{:elixir_make, "~> 0.7", [hex: :elixir_make, repo: "hexpm", optional: false]}], "hexpm", "3427232caf0835f94680e5bcf082408a70b48ad68a5f5c0b02a3bea9f3a075b9"},
   "certifi": {:hex, :certifi, "2.15.0", "0e6e882fcdaaa0a5a9f2b3db55b1394dba07e8d6d9bcad08318fb604c6839712", [:rebar3], [], "hexpm", "b147ed22ce71d72eafdad94f055165c1c182f61a2ff49df28bcc71d1d5b94a60"},
   "chatterbox": {:hex, :ts_chatterbox, "0.15.1", "5cac4d15dd7ad61fc3c4415ce4826fc563d4643dee897a558ec4ea0b1c835c9c", [:rebar3], [{:hpack, "~> 0.3.0", [hex: :hpack_erl, repo: "hexpm", optional: false]}], "hexpm", "4f75b91451338bc0da5f52f3480fa6ef6e3a2aeecfc33686d6b3d0a0948f31aa"},
diff --git a/test/pears/slack_test.exs b/test/pears/slack_test.exs
index d90e759b..c8b0e01c 100644
--- a/test/pears/slack_test.exs
+++ b/test/pears/slack_test.exs
@@ -219,6 +219,19 @@ defmodule Pears.SlackTest do
       {:error, _} = Slack.send_message_to_team(name, "Hey, friends!")
       refute_receive {:send_message, _, _, _}
     end
+
+    test "returns an error instead of raising when the slack client blows up", %{name: name} do
+      channel = %{id: "UXXXXXXX", name: "random"}
+      {:ok, _} = Slack.save_team_channel(Details.empty(), name, channel)
+
+      # Simulates a transport-level failure such as the TLS handshake alert that
+      # crashed record-pears: the underlying client raises rather than returning.
+      expect(MockSlackClient, :send_message, fn _channel, _message, _token ->
+        raise "TLS client: ... Unsupported Certificate (key_usage_mismatch)"
+      end)
+
+      assert {:error, _} = Slack.send_message_to_team(name, "Hey, friends!")
+    end
   end
 
   describe "send_daily_pears_summary" do
diff --git a/test/pears_web/live/pairing_board_live_test.exs b/test/pears_web/live/pairing_board_live_test.exs
index 8325cf41..bdacddd2 100644
--- a/test/pears_web/live/pairing_board_live_test.exs
+++ b/test/pears_web/live/pairing_board_live_test.exs
@@ -1,6 +1,12 @@
 defmodule PearsWeb.TeamLiveTest do
   use PearsWeb.ConnCase, async: true
   import Phoenix.LiveViewTest
+  import Mox
+
+  alias Pears.Slack
+  alias Pears.SlackFixtures
+
+  setup :verify_on_exit!
 
   describe "when logged in" do
     setup :register_and_log_in_team
@@ -12,6 +18,44 @@ defmodule PearsWeb.TeamLiveTest do
     end
   end
 
+  describe "recording pears when Slack is failing" do
+    setup :register_and_log_in_team
+
+    setup %{team: team} do
+      stub(Pears.MockSlackClient, :retrieve_access_tokens, fn _code, _url ->
+        SlackFixtures.valid_token_response(%{access_token: "xoxb-test-token"})
+      end)
+
+      {:ok, _} = Slack.onboard_team(team.name, "valid_code")
+
+      {:ok, _} =
+        Slack.save_team_channel(Slack.Details.empty(), team.name, %{
+          id: "UXXXXXXX",
+          name: "random"
+        })
+
+      FeatureFlags.enable(:send_daily_pears_summary, for_actor: team)
+      :ok
+    end
+
+    test "Save still records and warns the user instead of crashing the board", %{conn: conn} do
+      {:ok, view, _html} = live(conn, ~p"/teams")
+      # The async Slack post runs in the LiveView process; allow the mock there.
+      allow(Pears.MockSlackClient, self(), view.pid)
+
+      stub(Pears.MockSlackClient, :send_message, fn _channel, _message, _token ->
+        raise "TLS client: ... Unsupported Certificate (key_usage_mismatch)"
+      end)
+
+      view |> element("button", "Save") |> render_click()
+
+      html = render(view)
+      assert html =~ "recorded"
+      assert html =~ "Slack summary could not be posted"
+      assert Process.alive?(view.pid)
+    end
+  end
+
   describe "when logged out" do
     test "when not logged in, redirects to login", %{conn: conn} do
       {:error, {:redirect, %{to: redirected_to}}} = live(conn, "/teams")