diff --git a/apps/language_server/lib/language_server/dialyzer/analyzer.ex b/apps/language_server/lib/language_server/dialyzer/analyzer.ex
index 7d653d62f..9c911d744 100644
--- a/apps/language_server/lib/language_server/dialyzer/analyzer.ex
+++ b/apps/language_server/lib/language_server/dialyzer/analyzer.ex
@@ -9,33 +9,41 @@ defmodule ElixirLS.LanguageServer.Dialyzer.Analyzer do
   # TODO remove this comment when OTP >= 25 is required
 
   # default warns taken from
-  # https://github.com/erlang/otp/blob/4ed7957623e5ccbd420a09a506bd6bc9930fe93c/lib/dialyzer/src/dialyzer_options.erl#L34
-  # macros defined in https://github.com/erlang/otp/blob/4ed7957623e5ccbd420a09a506bd6bc9930fe93c/lib/dialyzer/src/dialyzer.hrl#L36
-  # as of OTP 25
+  # https://github.com/erlang/otp/blob/928d03e6da416208fce7b9a7dbbfbb4f25d26c37/lib/dialyzer/src/dialyzer_options.erl#L34
+  # macros defined in https://github.com/erlang/otp/blob/928d03e6da416208fce7b9a7dbbfbb4f25d26c37/lib/dialyzer/src/dialyzer.hrl#L36
+  # as of OTP 26
   @default_warns [
-    :warn_behaviour,
-    :warn_bin_construction,
-    :warn_callgraph,
-    :warn_contract_range,
-    :warn_contract_syntax,
-    :warn_contract_types,
-    :warn_failing_call,
-    :warn_fun_app,
-    :warn_map_construction,
-    :warn_matching,
-    :warn_non_proper_list,
-    :warn_not_called,
-    :warn_opaque,
-    :warn_return_no_exit,
-    :warn_undefined_callbacks
-  ]
+                   :warn_behaviour,
+                   :warn_bin_construction,
+                   :warn_callgraph,
+                   :warn_contract_range,
+                   :warn_contract_syntax,
+                   :warn_contract_types,
+                   :warn_failing_call,
+                   :warn_fun_app,
+                   :warn_map_construction,
+                   :warn_matching,
+                   :warn_non_proper_list,
+                   :warn_not_called,
+                   :warn_opaque,
+                   :warn_return_no_exit,
+                   :warn_undefined_callbacks
+                 ] ++
+                   (if String.to_integer(System.otp_release()) >= 26 do
+                      [
+                        # warn_unknown is enabled by default since OTP 26
+                        :warn_unknown
+                      ]
+                    else
+                      []
+                    end)
+
   @non_default_warns [
                        :warn_contract_not_equal,
                        :warn_contract_subtype,
                        :warn_contract_supertype,
                        :warn_return_only_exit,
-                       :warn_umatched_return,
-                       :warn_unknown
+                       :warn_umatched_return
                      ] ++
                        (if String.to_integer(System.otp_release()) >= 25 do
                           [
@@ -45,6 +53,17 @@ defmodule ElixirLS.LanguageServer.Dialyzer.Analyzer do
                           ]
                         else
                           []
+                        end) ++
+                       (if String.to_integer(System.otp_release()) >= 26 do
+                          [
+                            # OTP >= 26 options
+                            :warn_overlapping_contract
+                          ]
+                        else
+                          [
+                            # warn_unknown is enabled by default since OTP 26
+                            :warn_unknown
+                          ]
                         end)
   @log_cache_length 10
 
@@ -162,7 +181,16 @@ defmodule ElixirLS.LanguageServer.Dialyzer.Analyzer do
   end
 
   def matching_tags(warn_opts) do
-    :dialyzer_options.build_warnings(warn_opts, @default_warns)
+    default_warns =
+      unless :persistent_term.get(:language_server_test_mode, false) do
+        @default_warns
+      else
+        # do not include warn_unknown in tests
+        # we build small PLT and this results in lots of warnings
+        @default_warns -- [:warn_unknown]
+      end
+
+    :dialyzer_options.build_warnings(warn_opts, default_warns)
   end
 
   defp main_loop(%__MODULE__{backend_pid: backend_pid} = state) do