diff --git a/.credo.exs b/.credo.exs
index 7dceb12..dbebfee 100644
--- a/.credo.exs
+++ b/.credo.exs
@@ -122,7 +122,7 @@
           #
           {Credo.Check.Refactor.Apply, []},
           {Credo.Check.Refactor.CondStatements, []},
-          {Credo.Check.Refactor.CyclomaticComplexity, [max_complexity: 12]},
+          {Credo.Check.Refactor.CyclomaticComplexity, [max_complexity: 11]},
           {Credo.Check.Refactor.FunctionArity, []},
           {Credo.Check.Refactor.LongQuoteBlocks, []},
           {Credo.Check.Refactor.MatchInCondition, []},
diff --git a/README.md b/README.md
index 8b87a2d..4ea3d54 100644
--- a/README.md
+++ b/README.md
@@ -30,7 +30,7 @@ as WebRTC multiplexes traffic on a single socket but PRs are welcomed
 ```elixir
 def deps do
   [
-    {:ex_ice, "~> 0.15.0"}
+    {:ex_ice, "~> 0.16.0"}
   ]
 end
 ```
diff --git a/lib/ex_ice/priv/ice_agent.ex b/lib/ex_ice/priv/ice_agent.ex
index 82a73ef..9235e34 100644
--- a/lib/ex_ice/priv/ice_agent.ex
+++ b/lib/ex_ice/priv/ice_agent.ex
@@ -943,63 +943,92 @@ defmodule ExICE.Priv.ICEAgent do
 
   def handle_ex_turn_msg(ice_agent, client_ref, msg) do
     tr_id_tr = find_gathering_transaction(ice_agent.gathering_transactions, client_ref)
-
     cand = find_relay_cand_by_client(Map.values(ice_agent.local_cands), client_ref)
 
     case {tr_id_tr, cand} do
-      {nil, nil} ->
-        ice_agent
+      {nil, nil} -> ice_agent
+      {{tr_id, tr}, nil} -> handle_ex_turn_msg_for_gathering_tx(ice_agent, tr_id, tr, msg)
+      {nil, cand} -> handle_ex_turn_msg_for_relay_cand(ice_agent, cand, msg)
+    end
+  end
 
-      {{tr_id, tr}, nil} ->
-        case ExTURN.Client.handle_message(tr.client, msg) do
-          {:ok, client} ->
-            tr = %{tr | client: client}
-            put_in(ice_agent.gathering_transactions[tr_id], tr)
+  defp handle_ex_turn_msg_for_gathering_tx(ice_agent, tr_id, tr, msg) do
+    case ExTURN.Client.handle_message(tr.client, msg) do
+      {:ok, client} ->
+        put_in(ice_agent.gathering_transactions[tr_id], %{tr | client: client})
 
-          {:send, dst, data, client} ->
-            tr = %{tr | client: client}
-            :ok = ice_agent.transport_module.send(tr.socket, dst, data)
-            put_in(ice_agent.gathering_transactions[tr_id], tr)
+      {:send, dst, data, client} ->
+        send_on_gathering_tx(ice_agent, tr_id, %{tr | client: client}, dst, data)
 
-          {:error, _reason, _client} ->
-            {_, ice_agent} = pop_in(ice_agent.gathering_transactions[tr_id])
-            update_gathering_state(ice_agent)
-        end
+      {:error, _reason, _client} ->
+        drop_gathering_transaction(ice_agent, tr_id)
+    end
+  end
 
-      {nil, cand} ->
-        case ExTURN.Client.handle_message(cand.client, msg) do
-          {:ok, client} ->
-            cand = %{cand | client: client}
-            put_in(ice_agent.local_cands[cand.base.id], cand)
-
-          {:send, dst, data, client} ->
-            cand = %{cand | client: client}
-            ice_agent = put_in(ice_agent.local_cands[cand.base.id], cand)
-            # we can't use do_send here as it will try to create permission for the turn address
-            :ok = ice_agent.transport_module.send(cand.base.socket, dst, data)
-            ice_agent
+  defp send_on_gathering_tx(ice_agent, tr_id, tr, dst, data) do
+    case ice_agent.transport_module.send(tr.socket, dst, data) do
+      :ok ->
+        put_in(ice_agent.gathering_transactions[tr_id], tr)
+
+      {:error, _reason} ->
+        drop_gathering_transaction(ice_agent, tr_id)
+    end
+  end
+
+  defp drop_gathering_transaction(ice_agent, tr_id) do
+    {_, ice_agent} = pop_in(ice_agent.gathering_transactions[tr_id])
+    update_gathering_state(ice_agent)
+  end
 
-          {:permission_expired, _ip, client} ->
-            cand = %{cand | client: client}
-            put_in(ice_agent.local_cands[cand.base.id], cand)
+  defp handle_ex_turn_msg_for_relay_cand(ice_agent, cand, msg) do
+    case ExTURN.Client.handle_message(cand.client, msg) do
+      {:ok, client} ->
+        update_relay_cand_client(ice_agent, cand, client)
 
-          {:channel_expired, _addr, client} ->
-            cand = %{cand | client: client}
-            put_in(ice_agent.local_cands[cand.base.id], cand)
+      {:send, dst, data, client} ->
+        send_on_relay_cand(ice_agent, cand, client, dst, data)
 
-          {:error, _reason, client} ->
-            Logger.debug("""
-            Couldn't handle TURN message on candidate: #{inspect(cand)}. \
-            Closing candidate.\
-            """)
+      {:permission_expired, _ip, client} ->
+        update_relay_cand_client(ice_agent, cand, client)
 
-            cand = %{cand | client: client}
-            ice_agent = put_in(ice_agent.local_cands[cand.base.id], cand)
-            close_candidate(ice_agent, cand)
-        end
+      {:channel_expired, _addr, client} ->
+        update_relay_cand_client(ice_agent, cand, client)
+
+      {:error, _reason, client} ->
+        Logger.debug("""
+        Couldn't handle TURN message on candidate: #{inspect(cand)}. \
+        Closing candidate.\
+        """)
+
+        ice_agent
+        |> update_relay_cand_client(cand, client)
+        |> close_candidate(cand)
     end
   end
 
+  # we can't use do_send here as it will try to create permission for the turn address
+  defp send_on_relay_cand(ice_agent, cand, client, dst, data) do
+    cand = %{cand | client: client}
+    ice_agent = put_in(ice_agent.local_cands[cand.base.id], cand)
+
+    case ice_agent.transport_module.send(cand.base.socket, dst, data) do
+      :ok ->
+        ice_agent
+
+      {:error, _reason} ->
+        Logger.debug("""
+        Couldn't send TURN message on candidate: #{inspect(cand)}. \
+        Closing candidate.\
+        """)
+
+        close_candidate(ice_agent, cand)
+    end
+  end
+
+  defp update_relay_cand_client(ice_agent, cand, client) do
+    put_in(ice_agent.local_cands[cand.base.id], %{cand | client: client})
+  end
+
   @spec close(t()) :: t()
   def close(%__MODULE__{state: :closed} = ice_agent) do
     ice_agent
@@ -1283,8 +1312,16 @@ defmodule ExICE.Priv.ICEAgent do
 
       {:send, turn_addr, data, client} ->
         tr = %{tr | client: client}
-        :ok = ice_agent.transport_module.send(tr.socket, turn_addr, data)
-        put_in(ice_agent.gathering_transactions[tr_id], tr)
+
+        case ice_agent.transport_module.send(tr.socket, turn_addr, data) do
+          :ok ->
+            put_in(ice_agent.gathering_transactions[tr_id], tr)
+
+          {:error, _reason} ->
+            Logger.debug("Failed to create TURN allocation.")
+            {_, ice_agent} = pop_in(ice_agent.gathering_transactions[tr_id])
+            ice_agent
+        end
 
       {:error, _reason, _client} ->
         Logger.debug("Failed to create TURN allocation.")
@@ -2019,16 +2056,27 @@ defmodule ExICE.Priv.ICEAgent do
     ice_agent
   end
 
-  defp handle_keepalive_response(
+  defp handle_keepalive_response(ice_agent, local_cand, src_ip, src_port, msg) do
+    {pair_id, ice_agent} = pop_in(ice_agent.keepalives[msg.transaction_id])
+
+    case Map.fetch(ice_agent.checklist, pair_id) do
+      {:ok, %CandidatePair{} = pair} ->
+        handle_keepalive_response_on_pair(ice_agent, local_cand, src_ip, src_port, msg, pair)
+
+      :error ->
+        Logger.debug("Ignoring keepalive response for pruned pair #{inspect(pair_id)}")
+        ice_agent
+    end
+  end
+
+  defp handle_keepalive_response_on_pair(
          ice_agent,
          local_cand,
          src_ip,
          src_port,
-         %Message{type: %Type{class: :success_response}} = msg
+         %Message{type: %Type{class: :success_response}} = msg,
+         pair
        ) do
-    {pair_id, ice_agent} = pop_in(ice_agent.keepalives[msg.transaction_id])
-    %CandidatePair{} = pair = Map.fetch!(ice_agent.checklist, pair_id)
-
     with true <- symmetric?(ice_agent, local_cand.base.socket, {src_ip, src_port}, pair),
          :ok <- authenticate_msg(msg, ice_agent.remote_pwd) do
       Logger.debug("Received keepalive success response on: #{pair_info(ice_agent, pair)}")
@@ -2045,7 +2093,7 @@ defmodule ExICE.Priv.ICEAgent do
         ka_local_cand = Map.fetch!(ice_agent.local_cands, pair.local_cand_id)
         ka_remote_cand = Map.fetch!(ice_agent.remote_cands, pair.remote_cand_id)
 
-        pair = %CandidatePair{
+        pair = %{
           pair
           | non_symmetric_responses_received: pair.non_symmetric_responses_received + 1
         }
@@ -2068,20 +2116,19 @@ defmodule ExICE.Priv.ICEAgent do
         Not refreshing last_seen time.\
         """)
 
-        pair = %CandidatePair{pair | responses_received: pair.responses_received + 1}
+        pair = %{pair | responses_received: pair.responses_received + 1}
         put_in(ice_agent.checklist[pair.id], pair)
     end
   end
 
-  defp handle_keepalive_response(
+  defp handle_keepalive_response_on_pair(
          ice_agent,
          local_cand,
          src_ip,
          src_port,
-         %Message{type: %Type{class: :error_response}} = msg
+         %Message{type: %Type{class: :error_response}},
+         pair
        ) do
-    {pair_id, ice_agent} = pop_in(ice_agent.keepalives[msg.transaction_id])
-    %CandidatePair{} = pair = Map.fetch!(ice_agent.checklist, pair_id)
     pair = %{pair | responses_received: pair.responses_received + 1}
     ice_agent = put_in(ice_agent.checklist[pair.id], pair)
 
diff --git a/mix.exs b/mix.exs
index 7801057..11dcf03 100644
--- a/mix.exs
+++ b/mix.exs
@@ -1,7 +1,7 @@
 defmodule ExICE.MixProject do
   use Mix.Project
 
-  @version "0.15.0"
+  @version "0.16.0"
   @source_url "https://github.com/elixir-webrtc/ex_ice"
 
   def project do
diff --git a/test/priv/ice_agent_test.exs b/test/priv/ice_agent_test.exs
index 0bd08dc..c400240 100644
--- a/test/priv/ice_agent_test.exs
+++ b/test/priv/ice_agent_test.exs
@@ -750,6 +750,62 @@ defmodule ExICE.Priv.ICEAgentTest do
       assert new_pair.last_seen == pair.last_seen
       assert new_pair.responses_received == pair.responses_received + 1
     end
+
+    test "success response for pruned pair", %{ice_agent: ice_agent} do
+      ice_agent = connect(ice_agent)
+
+      [socket] = ice_agent.sockets
+      [remote_cand] = Map.values(ice_agent.remote_cands)
+      [pair] = Map.values(ice_agent.checklist)
+
+      ice_agent = ICEAgent.handle_keepalive_timeout(ice_agent, pair.id)
+      assert packet = Transport.Mock.recv(socket)
+      assert {:ok, req} = ExSTUN.Message.decode(packet)
+
+      resp =
+        binding_response(
+          req.transaction_id,
+          ice_agent.transport_module,
+          socket,
+          ice_agent.remote_pwd
+        )
+
+      {_, ice_agent} = pop_in(ice_agent.checklist[pair.id])
+      assert ice_agent.checklist == %{}
+
+      ice_agent =
+        ICEAgent.handle_udp(ice_agent, socket, remote_cand.address, remote_cand.port, resp)
+
+      assert ice_agent.checklist == %{}
+      assert ice_agent.keepalives == %{}
+    end
+
+    test "error response for pruned pair", %{ice_agent: ice_agent} do
+      ice_agent = connect(ice_agent)
+
+      [socket] = ice_agent.sockets
+      [remote_cand] = Map.values(ice_agent.remote_cands)
+      [pair] = Map.values(ice_agent.checklist)
+
+      ice_agent = ICEAgent.handle_keepalive_timeout(ice_agent, pair.id)
+      assert packet = Transport.Mock.recv(socket)
+      assert {:ok, req} = ExSTUN.Message.decode(packet)
+
+      resp =
+        Message.new(req.transaction_id, %Type{class: :error_response, method: :binding}, [
+          %ErrorCode{code: 400}
+        ])
+        |> Message.encode()
+
+      {_, ice_agent} = pop_in(ice_agent.checklist[pair.id])
+      assert ice_agent.checklist == %{}
+
+      ice_agent =
+        ICEAgent.handle_udp(ice_agent, socket, remote_cand.address, remote_cand.port, resp)
+
+      assert ice_agent.checklist == %{}
+      assert ice_agent.keepalives == %{}
+    end
   end
 
   describe "incoming binding request" do
@@ -2663,6 +2719,77 @@ defmodule ExICE.Priv.ICEAgentTest do
       refute Map.has_key?(cand.client.channel_addr, channel_number)
     end
 
+    test "send failure on gathering transaction via handle_ex_turn_msg", %{
+      ice_agent: ice_agent
+    } do
+      [socket] = ice_agent.sockets
+
+      ice_agent = ICEAgent.handle_ta_timeout(ice_agent)
+      req = read_allocate_request(socket)
+      resp = allocate_error_response(req.transaction_id)
+
+      turn_tr_id = {socket, {@turn_ip, @turn_port}}
+      tr = Map.fetch!(ice_agent.gathering_transactions, turn_tr_id)
+
+      Transport.Mock.fail_send(socket)
+
+      ice_agent =
+        ICEAgent.handle_ex_turn_msg(
+          ice_agent,
+          tr.client.ref,
+          {:socket_data, @turn_ip, @turn_port, resp}
+        )
+
+      assert ice_agent.gathering_transactions == %{}
+    end
+
+    test "send failure on gathering transaction via handle_udp", %{ice_agent: ice_agent} do
+      [socket] = ice_agent.sockets
+
+      ice_agent = ICEAgent.handle_ta_timeout(ice_agent)
+      req = read_allocate_request(socket)
+      resp = allocate_error_response(req.transaction_id)
+
+      Transport.Mock.fail_send(socket)
+
+      ice_agent = ICEAgent.handle_udp(ice_agent, socket, @turn_ip, @turn_port, resp)
+
+      assert ice_agent.gathering_transactions == %{}
+
+      assert nil ==
+               ice_agent.local_cands
+               |> Map.values()
+               |> Enum.find(&(&1.base.type == :relay))
+    end
+
+    test "send failure on relay candidate", %{ice_agent: ice_agent} do
+      [socket] = ice_agent.sockets
+
+      ice_agent = ICEAgent.handle_ta_timeout(ice_agent)
+      req = read_allocate_request(socket)
+      resp = allocate_error_response(req.transaction_id)
+      ice_agent = ICEAgent.handle_udp(ice_agent, socket, @turn_ip, @turn_port, resp)
+      req = read_allocate_request(socket)
+      resp = allocate_success_response(req.transaction_id, ice_agent.transport_module, socket)
+      ice_agent = ICEAgent.handle_udp(ice_agent, socket, @turn_ip, @turn_port, resp)
+
+      cand = ice_agent.local_cands |> Map.values() |> Enum.find(&(&1.base.type == :relay))
+      assert %ExICE.Priv.Candidate.Relay{} = cand
+      refute cand.base.closed?
+
+      Transport.Mock.fail_send(socket)
+
+      ice_agent =
+        ICEAgent.handle_ex_turn_msg(
+          ice_agent,
+          cand.client.ref,
+          :refresh_alloc
+        )
+
+      updated_cand = ice_agent.local_cands[cand.base.id]
+      assert updated_cand.base.closed?
+    end
+
     test "invalid TURN URL" do
       ice_agent =
         ICEAgent.new(
diff --git a/test/support/transport/mock.ex b/test/support/transport/mock.ex
index 8d71f0a..e81be3d 100644
--- a/test/support/transport/mock.ex
+++ b/test/support/transport/mock.ex
@@ -26,6 +26,20 @@ defmodule ExICE.Support.Transport.Mock do
     end
   end
 
+  @spec fail_send(ExICE.Priv.Transport.socket()) :: :ok
+  def fail_send(ref) do
+    [{^ref, socket}] = :ets.lookup(:transport_mock, ref)
+    :ets.insert(:transport_mock, {ref, Map.put(socket, :fail_send, true)})
+    :ok
+  end
+
+  @spec unfail_send(ExICE.Priv.Transport.socket()) :: :ok
+  def unfail_send(ref) do
+    [{^ref, socket}] = :ets.lookup(:transport_mock, ref)
+    :ets.insert(:transport_mock, {ref, Map.delete(socket, :fail_send)})
+    :ok
+  end
+
   @spec recv(ExICE.Priv.Transport.socket()) :: binary() | nil
   def recv(ref) do
     case :ets.lookup(:transport_mock, ref) do
@@ -88,8 +102,13 @@ defmodule ExICE.Support.Transport.Mock do
   @impl true
   def send(ref, _dst, packet, _tp_opts \\ []) do
     [{^ref, %{state: :open} = socket}] = :ets.lookup(:transport_mock, ref)
-    :ets.insert(:transport_mock, {ref, %{socket | buf: socket.buf ++ [packet]}})
-    :ok
+
+    if socket[:fail_send] do
+      {:error, :closed}
+    else
+      :ets.insert(:transport_mock, {ref, %{socket | buf: socket.buf ++ [packet]}})
+      :ok
+    end
   end
 
   @impl true