diff --git a/apps/language_server/lib/language_server/dialyzer/analyzer.ex b/apps/language_server/lib/language_server/dialyzer/analyzer.ex
index 9c911d744..1d1a1b3c1 100644
--- a/apps/language_server/lib/language_server/dialyzer/analyzer.ex
+++ b/apps/language_server/lib/language_server/dialyzer/analyzer.ex
@@ -180,6 +180,8 @@ defmodule ElixirLS.LanguageServer.Dialyzer.Analyzer do
     main_loop(state)
   end
 
+  def all_warns, do: @default_warns ++ @non_default_warns
+
   def matching_tags(warn_opts) do
     default_warns =
       unless :persistent_term.get(:language_server_test_mode, false) do
diff --git a/apps/language_server/lib/language_server/server.ex b/apps/language_server/lib/language_server/server.ex
index a3ef09fd7..d10be5327 100644
--- a/apps/language_server/lib/language_server/server.ex
+++ b/apps/language_server/lib/language_server/server.ex
@@ -1787,6 +1787,24 @@ defmodule ElixirLS.LanguageServer.Server do
         else
           IO.warn("Invalid `dialyzerWarnOpts` #{inspect(dialyzer_warn_opts)}")
         end
+
+        all_warns = ElixirLS.LanguageServer.Dialyzer.Analyzer.all_warns() |> Enum.map(&to_string/1)
+
+        for opt <- dialyzer_warn_opts, opt not in all_warns do
+          Logger.error("Invalid `dialyzerWarnOpts`: unknown warning option `#{opt}`")
+
+          JsonRpc.show_message(
+            :error,
+            "Invalid `dialyzerWarnOpts` in configuration. Unknown warning option `#{opt}`."
+          )
+
+          unless :persistent_term.get(:language_server_test_mode, false) do
+            Process.sleep(2000)
+            System.halt(1)
+          else
+            IO.warn("Invalid `dialyzerWarnOpts`: unknown warning option `#{opt}`")
+          end
+        end
       end
 
       dialyzer_formats = [