diff --git a/apps/elixir_ls_debugger/lib/debugger/variables.ex b/apps/elixir_ls_debugger/lib/debugger/variables.ex
index f86a4309a..8aeec8931 100644
--- a/apps/elixir_ls_debugger/lib/debugger/variables.ex
+++ b/apps/elixir_ls_debugger/lib/debugger/variables.ex
@@ -66,6 +66,7 @@ defmodule ElixirLS.Debugger.Variables do
     children =
       var
       |> Map.to_list()
+      |> Enum.sort()
       |> Enum.slice(start || 0, count || map_size(var))
 
     for {key, value} <- children do
diff --git a/apps/elixir_ls_utils/lib/output_device.ex b/apps/elixir_ls_utils/lib/output_device.ex
index 2594bdddd..344319b7b 100644
--- a/apps/elixir_ls_utils/lib/output_device.ex
+++ b/apps/elixir_ls_utils/lib/output_device.ex
@@ -9,7 +9,11 @@ defmodule ElixirLS.Utils.OutputDevice do
   ## Client API
 
   def start_link(device, output_fn) do
-    Task.start_link(fn -> loop({device, output_fn}) end)
+    Task.start_link(fn ->
+      # Trap exit to make sure the process completes :io_request handling before exiting
+      Process.flag(:trap_exit, true)
+      loop({device, output_fn})
+    end)
   end
 
   def child_spec(arguments) do
@@ -22,12 +26,13 @@ defmodule ElixirLS.Utils.OutputDevice do
     }
   end
 
-  def get_opts, do: @opts
-
   ## Implementation
 
   defp loop(state) do
     receive do
+      {:EXIT, _from, reason} ->
+        exit(reason)
+
       {:io_request, from, reply_as, request} ->
         result = io_request(request, state, reply_as)
         send(from, {:io_reply, reply_as, result})
@@ -82,6 +87,8 @@ defmodule ElixirLS.Utils.OutputDevice do
   end
 
   defp io_request({:setopts, new_opts}, _state, _reply_as) do
+    # we do not support changing opts
+    # only validate that the passed ones match defaults
     validate_otps(new_opts, {:ok, 0})
   end
 
diff --git a/apps/elixir_ls_utils/lib/packet_stream.ex b/apps/elixir_ls_utils/lib/packet_stream.ex
index 1235321fb..4a9c1accd 100644
--- a/apps/elixir_ls_utils/lib/packet_stream.ex
+++ b/apps/elixir_ls_utils/lib/packet_stream.ex
@@ -3,10 +3,17 @@ defmodule ElixirLS.Utils.PacketStream do
   Reads from an IO device and provides a stream of incoming packets
   """
 
-  def stream(pid \\ Process.group_leader()) do
-    if is_pid(pid) do
-      :ok = :io.setopts(pid, binary: true, encoding: :latin1)
-    end
+  def stream(pid, halt_on_error? \\ false) when is_pid(pid) do
+    stream_pid = self()
+
+    Task.start_link(fn ->
+      ref = Process.monitor(pid)
+
+      receive do
+        {:DOWN, ^ref, :process, _pid, reason} ->
+          send(stream_pid, {:exit_reason, reason})
+      end
+    end)
 
     Stream.resource(
       fn -> :ok end,
@@ -31,7 +38,31 @@ defmodule ElixirLS.Utils.PacketStream do
           :ok
 
         {:error, reason} ->
-          raise "Unable to read from device: #{inspect(reason)}"
+          "Unable to read from input device: #{inspect(reason)}"
+
+          error_message =
+            unless Process.alive?(pid) do
+              receive do
+                {:exit_reason, exit_reason} ->
+                  "Input device terminated: #{inspect(exit_reason)}"
+              after
+                500 -> "Input device terminated"
+              end
+            else
+              "Unable to read from device: #{inspect(reason)}"
+            end
+
+          if halt_on_error? do
+            if ElixirLS.Utils.WireProtocol.io_intercepted?() do
+              ElixirLS.Utils.WireProtocol.undo_intercept_output()
+            end
+
+            IO.puts(:stderr, error_message)
+
+            System.halt(1)
+          else
+            raise error_message
+          end
       end
     )
   end
diff --git a/apps/elixir_ls_utils/lib/wire_protocol.ex b/apps/elixir_ls_utils/lib/wire_protocol.ex
index 8e0450319..502d1e7b8 100644
--- a/apps/elixir_ls_utils/lib/wire_protocol.ex
+++ b/apps/elixir_ls_utils/lib/wire_protocol.ex
@@ -23,33 +23,93 @@ defmodule ElixirLS.Utils.WireProtocol do
   end
 
   def io_intercepted? do
-    !!Process.whereis(:raw_user)
+    !!Process.whereis(:raw_standard_error)
   end
 
   def intercept_output(print_fn, print_err_fn) do
     raw_user = Process.whereis(:user)
     raw_standard_error = Process.whereis(:standard_error)
 
-    :ok = :io.setopts(raw_user, OutputDevice.get_opts())
+    :ok = :io.setopts(raw_user, binary: true, encoding: :latin1)
 
-    {:ok, user} = OutputDevice.start_link(raw_user, print_fn)
-    {:ok, standard_error} = OutputDevice.start_link(raw_user, print_err_fn)
+    {:ok, intercepted_user} = OutputDevice.start_link(raw_user, print_fn)
+    {:ok, intercepted_standard_error} = OutputDevice.start_link(raw_user, print_err_fn)
 
     Process.unregister(:user)
     Process.register(raw_user, :raw_user)
-    Process.register(user, :user)
+    Process.register(intercepted_user, :user)
 
     Process.unregister(:standard_error)
     Process.register(raw_standard_error, :raw_standard_error)
-    Process.register(standard_error, :standard_error)
+    Process.register(intercepted_standard_error, :standard_error)
 
-    for process <- :erlang.processes(), process not in [raw_user, raw_standard_error] do
-      Process.group_leader(process, user)
+    for process <- :erlang.processes(),
+        process not in [
+          raw_user,
+          raw_standard_error,
+          intercepted_user,
+          intercepted_standard_error
+        ] do
+      Process.group_leader(process, intercepted_user)
     end
   end
 
+  def undo_intercept_output() do
+    intercepted_user = Process.whereis(:user)
+    intercepted_standard_error = Process.whereis(:standard_error)
+
+    Process.unregister(:user)
+
+    raw_user =
+      try do
+        raw_user = Process.whereis(:raw_user)
+        Process.unregister(:raw_user)
+        Process.register(raw_user, :user)
+        raw_user
+      rescue
+        ArgumentError -> nil
+      end
+
+    Process.unregister(:standard_error)
+
+    raw_standard_error =
+      try do
+        raw_standard_error = Process.whereis(:raw_standard_error)
+        Process.unregister(:raw_standard_error)
+        Process.register(raw_standard_error, :standard_error)
+        raw_user
+      rescue
+        ArgumentError -> nil
+      end
+
+    if raw_user do
+      for process <- :erlang.processes(),
+          process not in [
+            raw_user,
+            raw_standard_error,
+            intercepted_user,
+            intercepted_standard_error
+          ] do
+        Process.group_leader(process, raw_user)
+      end
+    else
+      init = :erlang.processes() |> hd
+
+      for process <- :erlang.processes(),
+          process not in [raw_standard_error, intercepted_user, intercepted_standard_error] do
+        Process.group_leader(process, init)
+      end
+    end
+
+    Process.unlink(intercepted_user)
+    Process.unlink(intercepted_standard_error)
+
+    Process.exit(intercepted_user, :kill)
+    Process.exit(intercepted_standard_error, :kill)
+  end
+
   def stream_packets(receive_packets_fn) do
-    PacketStream.stream(Process.whereis(:raw_user))
+    PacketStream.stream(Process.whereis(:raw_user), true)
     |> Stream.each(fn packet -> receive_packets_fn.(packet) end)
     |> Stream.run()
   end
diff --git a/apps/elixir_ls_utils/priv/debugger.bat b/apps/elixir_ls_utils/priv/debugger.bat
index 04c00bf8a..57089cb3d 100755
--- a/apps/elixir_ls_utils/priv/debugger.bat
+++ b/apps/elixir_ls_utils/priv/debugger.bat
@@ -6,4 +6,4 @@ IF EXIST "%APPDATA%\elixir_ls\setup.bat" (
 )
 
 SET ERL_LIBS=%~dp0;%ERL_LIBS%
-elixir %ELS_ELIXIR_OPTS% --erl "+sbwt none +sbwtdcpu none +sbwtdio none %ELS_ERL_OPTS%" -e "ElixirLS.Debugger.CLI.main()"
+elixir %ELS_ELIXIR_OPTS% --erl "-kernel standard_io_encoding latin1 +sbwt none +sbwtdcpu none +sbwtdio none %ELS_ERL_OPTS%" -e "ElixirLS.Debugger.CLI.main()"
diff --git a/apps/elixir_ls_utils/priv/language_server.bat b/apps/elixir_ls_utils/priv/language_server.bat
index c14e3cf09..0de4b6349 100755
--- a/apps/elixir_ls_utils/priv/language_server.bat
+++ b/apps/elixir_ls_utils/priv/language_server.bat
@@ -6,4 +6,4 @@ IF EXIST "%APPDATA%\elixir_ls\setup.bat" (
 )
 
 SET ERL_LIBS=%~dp0;%ERL_LIBS%
-elixir %ELS_ELIXIR_OPTS% --erl "+sbwt none +sbwtdcpu none +sbwtdio none %ELS_ERL_OPTS%" -e "ElixirLS.LanguageServer.CLI.main()"
+elixir %ELS_ELIXIR_OPTS% --erl "-kernel standard_io_encoding latin1 +sbwt none +sbwtdcpu none +sbwtdio none %ELS_ERL_OPTS%" -e "ElixirLS.LanguageServer.CLI.main()"
diff --git a/apps/elixir_ls_utils/priv/launch.sh b/apps/elixir_ls_utils/priv/launch.sh
index 2364526d6..c434c5ccd 100755
--- a/apps/elixir_ls_utils/priv/launch.sh
+++ b/apps/elixir_ls_utils/priv/launch.sh
@@ -79,4 +79,4 @@ fi
 
 export ERL_LIBS="$SCRIPTPATH:$ERL_LIBS"
 
-exec elixir $ELS_ELIXIR_OPTS --erl "+sbwt none +sbwtdcpu none +sbwtdio none $ELS_ERL_OPTS" -e "$ELS_SCRIPT"
+exec elixir $ELS_ELIXIR_OPTS --erl "-kernel standard_io_encoding latin1 +sbwt none +sbwtdcpu none +sbwtdio none $ELS_ERL_OPTS" -e "$ELS_SCRIPT"
diff --git a/apps/language_server/lib/language_server/dialyzer/analyzer.ex b/apps/language_server/lib/language_server/dialyzer/analyzer.ex
index 0d8e5dc79..ecee353f4 100644
--- a/apps/language_server/lib/language_server/dialyzer/analyzer.ex
+++ b/apps/language_server/lib/language_server/dialyzer/analyzer.ex
@@ -96,6 +96,26 @@ defmodule ElixirLS.LanguageServer.Dialyzer.Analyzer do
     solvers: :undefined
   )
 
+  Record.defrecordp(
+    :analysis_26,
+    :analysis,
+    analysis_pid: :undefined,
+    type: :succ_typings,
+    defines: [],
+    doc_plt: :undefined,
+    files: [],
+    include_dirs: [],
+    start_from: :byte_code,
+    plt: :undefined,
+    use_contracts: true,
+    behaviours_chk: false,
+    timing: false,
+    timing_server: :none,
+    callgraph_file: [],
+    mod_deps_file: [],
+    solvers: :undefined
+  )
+
   def analyze(active_plt, []) do
     {active_plt, %{}, []}
   end
@@ -110,12 +130,19 @@ defmodule ElixirLS.LanguageServer.Dialyzer.Analyzer do
             solvers: []
           )
 
-        _ ->
+        25 ->
           analysis_25(
             plt: active_plt,
             files: files,
             solvers: []
           )
+
+        _ ->
+          analysis_26(
+            plt: active_plt,
+            files: files,
+            solvers: []
+          )
       end
 
     parent = self()
diff --git a/apps/language_server/lib/language_server/dialyzer/manifest.ex b/apps/language_server/lib/language_server/dialyzer/manifest.ex
index d86041c47..7d1677d34 100644
--- a/apps/language_server/lib/language_server/dialyzer/manifest.ex
+++ b/apps/language_server/lib/language_server/dialyzer/manifest.ex
@@ -106,14 +106,15 @@ defmodule ElixirLS.LanguageServer.Dialyzer.Manifest do
       exported_types_list
     } = File.read!(manifest_path) |> :erlang.binary_to_term()
 
-    # FIXME: matching against opaque type
+    active_plt = :dialyzer_plt.new()
+
     plt(
       info: info,
       types: types,
       contracts: contracts,
       callbacks: callbacks,
       exported_types: exported_types
-    ) = active_plt = apply(:dialyzer_plt, :new, [])
+    ) = active_plt
 
     for item <- info_list, do: :ets.insert(info, item)
     for item <- types_list, do: :ets.insert(types, item)
@@ -127,7 +128,11 @@ defmodule ElixirLS.LanguageServer.Dialyzer.Manifest do
   end
 
   def load_elixir_plt() do
-    apply(:dialyzer_plt, :from_file, [to_charlist(elixir_plt_path())])
+    if String.to_integer(System.otp_release()) < 26 do
+      :dialyzer_plt.from_file(to_charlist(elixir_plt_path()))
+    else
+      :dialyzer_cplt.from_file(to_charlist(elixir_plt_path()))
+    end
   rescue
     _ -> build_elixir_plt()
   catch
@@ -175,7 +180,12 @@ defmodule ElixirLS.LanguageServer.Dialyzer.Manifest do
     )
 
     JsonRpc.show_message(:info, "Saved Elixir PLT to #{elixir_plt_path()}")
-    :dialyzer_plt.from_file(to_charlist(elixir_plt_path()))
+
+    if String.to_integer(System.otp_release()) < 26 do
+      :dialyzer_plt.from_file(to_charlist(elixir_plt_path()))
+    else
+      :dialyzer_cplt.from_file(to_charlist(elixir_plt_path()))
+    end
   end
 
   defp otp_vsn() do
diff --git a/scripts/debugger.bat b/scripts/debugger.bat
index 4c87e1905..0fecba623 100755
--- a/scripts/debugger.bat
+++ b/scripts/debugger.bat
@@ -13,4 +13,4 @@ SET MIX_ENV=prod
 @REM elixir is a batch script and needs to be called
 ECHO "" | CALL elixir "%~dp0quiet_install.exs" > nul
 IF %ERRORLEVEL% NEQ 0 EXIT 1
-elixir %ELS_ELIXIR_OPTS% --erl "+sbwt none +sbwtdcpu none +sbwtdio none %ELS_ERL_OPTS%" "%~dp0launch.exs"
+elixir %ELS_ELIXIR_OPTS% --erl "-kernel standard_io_encoding latin1 +sbwt none +sbwtdcpu none +sbwtdio none %ELS_ERL_OPTS%" "%~dp0launch.exs"
diff --git a/scripts/language_server.bat b/scripts/language_server.bat
index e035ff412..6bfae24d9 100755
--- a/scripts/language_server.bat
+++ b/scripts/language_server.bat
@@ -13,4 +13,4 @@ SET MIX_ENV=prod
 @REM elixir is a batch script and needs to be called
 ECHO "" | CALL elixir "%~dp0quiet_install.exs" >nul
 IF %ERRORLEVEL% NEQ 0 EXIT 1
-elixir %ELS_ELIXIR_OPTS% --erl "+sbwt none +sbwtdcpu none +sbwtdio none %ELS_ERL_OPTS%" "%~dp0launch.exs"
+elixir %ELS_ELIXIR_OPTS% --erl "-kernel standard_io_encoding latin1 +sbwt none +sbwtdcpu none +sbwtdio none %ELS_ERL_OPTS%" "%~dp0launch.exs"
diff --git a/scripts/launch.sh b/scripts/launch.sh
index aa0acd5f4..f31d4bebd 100755
--- a/scripts/launch.sh
+++ b/scripts/launch.sh
@@ -82,4 +82,4 @@ export MIX_ENV=prod
 # we need to make sure it doesn't interfere with LSP/DAP
 echo "" | elixir "$SCRIPTPATH/quiet_install.exs" >/dev/null || exit 1
 
-exec elixir $ELS_ELIXIR_OPTS --erl "+sbwt none +sbwtdcpu none +sbwtdio none $ELS_ERL_OPTS" "$SCRIPTPATH/launch.exs"
+exec elixir $ELS_ELIXIR_OPTS --erl "-kernel standard_io_encoding latin1 +sbwt none +sbwtdcpu none +sbwtdio none $ELS_ERL_OPTS" "$SCRIPTPATH/launch.exs"