diff --git a/libcxx/docs/Status/Cxx2cIssues.csv b/libcxx/docs/Status/Cxx2cIssues.csv
--- a/libcxx/docs/Status/Cxx2cIssues.csv
+++ b/libcxx/docs/Status/Cxx2cIssues.csv
@@ -14,7 +14,7 @@
 "`3925 <https://wg21.link/LWG3925>`__","Concept ``formattable``'s definition is incorrect","Varna June 2023","|Complete|","17.0","|format|"
 "`3927 <https://wg21.link/LWG3927>`__","Unclear preconditions for ``operator[]`` for sequence containers","Varna June 2023","|Nothing To Do|","",""
 "`3935 <https://wg21.link/LWG3935>`__","``template<class X> constexpr complex& operator=(const complex<X>&)`` has no specification","Varna June 2023","|Complete|","3.4",""
-"`3938 <https://wg21.link/LWG3938>`__","Cannot use ``std::expected`` monadic ops with move-only ``error_type``","Varna June 2023","","",""
+"`3938 <https://wg21.link/LWG3938>`__","Cannot use ``std::expected`` monadic ops with move-only ``error_type``","Varna June 2023","|Complete|","17.0",""
 "`3940 <https://wg21.link/LWG3940>`__","``std::expected<void, E>::value()`` also needs ``E`` to be copy constructible","Varna June 2023","","",""
 "","","","","",""
 "`3343 <https://wg21.link/LWG3343>`__","Ordering of calls to ``unlock()`` and ``notify_all()`` in Effects element of ``notify_all_at_thread_exit()`` should be reversed","Not Yet Adopted","|Complete|","16.0",""
diff --git a/libcxx/include/__expected/expected.h b/libcxx/include/__expected/expected.h
--- a/libcxx/include/__expected/expected.h
+++ b/libcxx/include/__expected/expected.h
@@ -644,7 +644,7 @@
     static_assert(is_same_v<typename _Up::error_type, _Err>,
                   "The result of f(value()) must have the same error_type as this expected");
     if (has_value()) {
-      return std::invoke(std::forward<_Func>(__f), value());
+      return std::invoke(std::forward<_Func>(__f), **this);
     }
     return _Up(unexpect, error());
   }
@@ -657,7 +657,7 @@
     static_assert(is_same_v<typename _Up::error_type, _Err>,
                   "The result of f(value()) must have the same error_type as this expected");
     if (has_value()) {
-      return std::invoke(std::forward<_Func>(__f), value());
+      return std::invoke(std::forward<_Func>(__f), **this);
     }
     return _Up(unexpect, error());
   }
@@ -671,7 +671,7 @@
     static_assert(is_same_v<typename _Up::error_type, _Err>,
                   "The result of f(std::move(value())) must have the same error_type as this expected");
     if (has_value()) {
-      return std::invoke(std::forward<_Func>(__f), std::move(value()));
+      return std::invoke(std::forward<_Func>(__f), std::move(**this));
     }
     return _Up(unexpect, std::move(error()));
   }
@@ -685,7 +685,7 @@
     static_assert(is_same_v<typename _Up::error_type, _Err>,
                   "The result of f(std::move(value())) must have the same error_type as this expected");
     if (has_value()) {
-      return std::invoke(std::forward<_Func>(__f), std::move(value()));
+      return std::invoke(std::forward<_Func>(__f), std::move(**this));
     }
     return _Up(unexpect, std::move(error()));
   }
@@ -698,7 +698,7 @@
     static_assert(is_same_v<typename _Gp::value_type, _Tp>,
                   "The result of f(error()) must have the same value_type as this expected");
     if (has_value()) {
-      return _Gp(in_place, value());
+      return _Gp(in_place, **this);
     }
     return std::invoke(std::forward<_Func>(__f), error());
   }
@@ -711,7 +711,7 @@
     static_assert(is_same_v<typename _Gp::value_type, _Tp>,
                   "The result of f(error()) must have the same value_type as this expected");
     if (has_value()) {
-      return _Gp(in_place, value());
+      return _Gp(in_place, **this);
     }
     return std::invoke(std::forward<_Func>(__f), error());
   }
@@ -725,7 +725,7 @@
     static_assert(is_same_v<typename _Gp::value_type, _Tp>,
                   "The result of f(std::move(error())) must have the same value_type as this expected");
     if (has_value()) {
-      return _Gp(in_place, std::move(value()));
+      return _Gp(in_place, std::move(**this));
     }
     return std::invoke(std::forward<_Func>(__f), std::move(error()));
   }
@@ -739,7 +739,7 @@
     static_assert(is_same_v<typename _Gp::value_type, _Tp>,
                   "The result of f(std::move(error())) must have the same value_type as this expected");
     if (has_value()) {
-      return _Gp(in_place, std::move(value()));
+      return _Gp(in_place, std::move(**this));
     }
     return std::invoke(std::forward<_Func>(__f), std::move(error()));
   }
@@ -752,9 +752,9 @@
       return expected<_Up, _Err>(unexpect, error());
     }
     if constexpr (!is_void_v<_Up>) {
-      return expected<_Up, _Err>(__expected_construct_in_place_from_invoke_tag{}, std::forward<_Func>(__f), value());
+      return expected<_Up, _Err>(__expected_construct_in_place_from_invoke_tag{}, std::forward<_Func>(__f), **this);
     } else {
-      std::invoke(std::forward<_Func>(__f), value());
+      std::invoke(std::forward<_Func>(__f), **this);
       return expected<_Up, _Err>();
     }
   }
@@ -767,9 +767,9 @@
       return expected<_Up, _Err>(unexpect, error());
     }
     if constexpr (!is_void_v<_Up>) {
-      return expected<_Up, _Err>(__expected_construct_in_place_from_invoke_tag{}, std::forward<_Func>(__f), value());
+      return expected<_Up, _Err>(__expected_construct_in_place_from_invoke_tag{}, std::forward<_Func>(__f), **this);
     } else {
-      std::invoke(std::forward<_Func>(__f), value());
+      std::invoke(std::forward<_Func>(__f), **this);
       return expected<_Up, _Err>();
     }
   }
@@ -783,9 +783,9 @@
     }
     if constexpr (!is_void_v<_Up>) {
       return expected<_Up, _Err>(
-          __expected_construct_in_place_from_invoke_tag{}, std::forward<_Func>(__f), std::move(value()));
+          __expected_construct_in_place_from_invoke_tag{}, std::forward<_Func>(__f), std::move(**this));
     } else {
-      std::invoke(std::forward<_Func>(__f), std::move(value()));
+      std::invoke(std::forward<_Func>(__f), std::move(**this));
       return expected<_Up, _Err>();
     }
   }
@@ -799,9 +799,9 @@
     }
     if constexpr (!is_void_v<_Up>) {
       return expected<_Up, _Err>(
-          __expected_construct_in_place_from_invoke_tag{}, std::forward<_Func>(__f), std::move(value()));
+          __expected_construct_in_place_from_invoke_tag{}, std::forward<_Func>(__f), std::move(**this));
     } else {
-      std::invoke(std::forward<_Func>(__f), std::move(value()));
+      std::invoke(std::forward<_Func>(__f), std::move(**this));
       return expected<_Up, _Err>();
     }
   }
@@ -813,7 +813,7 @@
     static_assert(__valid_std_unexpected<_Gp>::value,
                   "The result of f(error()) must be a valid template argument for unexpected");
     if (has_value()) {
-      return expected<_Tp, _Gp>(in_place, value());
+      return expected<_Tp, _Gp>(in_place, **this);
     }
     return expected<_Tp, _Gp>(__expected_construct_unexpected_from_invoke_tag{}, std::forward<_Func>(__f), error());
   }
@@ -825,7 +825,7 @@
     static_assert(__valid_std_unexpected<_Gp>::value,
                   "The result of f(error()) must be a valid template argument for unexpected");
     if (has_value()) {
-      return expected<_Tp, _Gp>(in_place, value());
+      return expected<_Tp, _Gp>(in_place, **this);
     }
     return expected<_Tp, _Gp>(__expected_construct_unexpected_from_invoke_tag{}, std::forward<_Func>(__f), error());
   }
@@ -837,7 +837,7 @@
     static_assert(__valid_std_unexpected<_Gp>::value,
                   "The result of f(std::move(error())) must be a valid template argument for unexpected");
     if (has_value()) {
-      return expected<_Tp, _Gp>(in_place, std::move(value()));
+      return expected<_Tp, _Gp>(in_place, std::move(**this));
     }
     return expected<_Tp, _Gp>(
         __expected_construct_unexpected_from_invoke_tag{}, std::forward<_Func>(__f), std::move(error()));
@@ -850,7 +850,7 @@
     static_assert(__valid_std_unexpected<_Gp>::value,
                   "The result of f(std::move(error())) must be a valid template argument for unexpected");
     if (has_value()) {
-      return expected<_Tp, _Gp>(in_place, std::move(value()));
+      return expected<_Tp, _Gp>(in_place, std::move(**this));
     }
     return expected<_Tp, _Gp>(
         __expected_construct_unexpected_from_invoke_tag{}, std::forward<_Func>(__f), std::move(error()));
diff --git a/libcxx/test/std/utilities/expected/expected.expected/monadic/and_then.pass.cpp b/libcxx/test/std/utilities/expected/expected.expected/monadic/and_then.pass.cpp
--- a/libcxx/test/std/utilities/expected/expected.expected/monadic/and_then.pass.cpp
+++ b/libcxx/test/std/utilities/expected/expected.expected/monadic/and_then.pass.cpp
@@ -22,6 +22,8 @@
 #include <type_traits>
 #include <utility>
 
+#include "../../types.h"
+
 struct LVal {
   constexpr std::expected<int, int> operator()(int&) { return 1; }
   std::expected<int, int> operator()(const int&)  = delete;
@@ -153,6 +155,7 @@
   {std::forward<E>(e).and_then(std::forward<F>(f))};
 };
 
+// clang-format off
 static_assert( has_and_then<std::expected<int, int>&, std::expected<int, int>(int&)>);
 static_assert(!has_and_then<std::expected<int, NonCopyable>&, std::expected<int, NonCopyable>(int&)>);
 static_assert( has_and_then<const std::expected<int, int>&, std::expected<int, int>(const int&)>);
@@ -166,7 +169,12 @@
 static_assert(!has_and_then<const std::expected<int, std::unique_ptr<int>>&, int()>);
 static_assert(!has_and_then<const std::expected<int, std::unique_ptr<int>>&&, int()>);
 
-// clang-format off
+// [LWG 3983] https://cplusplus.github.io/LWG/issue3938, check std::expected monadic ops well-formed with move-only error_type.
+static_assert(has_and_then<std::expected<int, CopyConstructibleErrorType>&, std::expected<int, CopyConstructibleErrorType>(int&)>);
+// There are no effects for `const &` overload, because the constraints requires is_constructible_v<E, decltype(error())> is true.
+static_assert(has_and_then<std::expected<int, MoveOnlyErrorType>&&, std::expected<int, MoveOnlyErrorType>(int)>);
+static_assert(has_and_then<const std::expected<int, MoveOnlyErrorType>&&, std::expected<int, MoveOnlyErrorType>(const int)>);
+
 constexpr void test_val_types() {
   // Test & overload
   {
diff --git a/libcxx/test/std/utilities/expected/expected.expected/monadic/or_else.pass.cpp b/libcxx/test/std/utilities/expected/expected.expected/monadic/or_else.pass.cpp
--- a/libcxx/test/std/utilities/expected/expected.expected/monadic/or_else.pass.cpp
+++ b/libcxx/test/std/utilities/expected/expected.expected/monadic/or_else.pass.cpp
@@ -22,6 +22,8 @@
 #include <type_traits>
 #include <utility>
 
+#include "../../types.h"
+
 struct LVal {
   constexpr std::expected<int, int> operator()(int&) { return 1; }
   std::expected<int, int> operator()(const int&)  = delete;
@@ -83,12 +85,17 @@
     requires(E&& e, F&& f) {
       { std::forward<E>(e).or_else(std::forward<F>(f)) };
     };
-
+// clang-format off
 // [LWG 3877] https://cplusplus.github.io/LWG/issue3877, check constraint failing but not compile error inside the function body.
 static_assert(!has_or_else<const std::expected<std::unique_ptr<int>, int>&, int()>);
 static_assert(!has_or_else<const std::expected<std::unique_ptr<int>, int>&&, int()>);
 
-// clang-format off
+// [LWG 3983] https://cplusplus.github.io/LWG/issue3938, check std::expected monadic ops well-formed with move-only error_type.
+static_assert(has_or_else<std::expected<int, CopyConstructibleErrorType>&, std::expected<int, int>(CopyConstructibleErrorType &)>);
+static_assert(has_or_else<const std::expected<int, CopyConstructibleErrorType>&, std::expected<int, int>(const CopyConstructibleErrorType &)>);
+static_assert(has_or_else<std::expected<int, MoveOnlyErrorType>&&, std::expected<int, int>(MoveOnlyErrorType&&)>);
+static_assert(has_or_else<const std::expected<int, MoveOnlyErrorType>&&, std::expected<int, int>(const MoveOnlyErrorType&&)>);
+
 constexpr void test_val_types() {
   // Test & overload
   {
diff --git a/libcxx/test/std/utilities/expected/expected.expected/monadic/transform.pass.cpp b/libcxx/test/std/utilities/expected/expected.expected/monadic/transform.pass.cpp
--- a/libcxx/test/std/utilities/expected/expected.expected/monadic/transform.pass.cpp
+++ b/libcxx/test/std/utilities/expected/expected.expected/monadic/transform.pass.cpp
@@ -26,6 +26,8 @@
 #include <type_traits>
 #include <utility>
 
+#include "../../types.h"
+
 struct LVal {
   constexpr int operator()(int&) { return 1; }
   int operator()(const int&)  = delete;
@@ -98,11 +100,17 @@
       { std::forward<E>(e).transform(std::forward<F>(f)) };
     };
 
+// clang-format off
 // [LWG 3877] https://cplusplus.github.io/LWG/issue3877, check constraint failing but not compile error inside the function body.
 static_assert(!has_transform<const std::expected<int, std::unique_ptr<int>>&, int()>);
 static_assert(!has_transform<const std::expected<int, std::unique_ptr<int>>&&, int()>);
 
-// clang-format off
+// [LWG 3983] https://cplusplus.github.io/LWG/issue3938, check std::expected monadic ops well-formed with move-only error_type.
+static_assert(has_transform<std::expected<int, CopyConstructibleErrorType>&, int(int&)>);
+// There are no effects for `const &` overload, because the constraints requires is_constructible_v<E, decltype(error())> is true.
+static_assert(has_transform<std::expected<int, MoveOnlyErrorType>&&, int(int)>);
+static_assert(has_transform<const std::expected<int, MoveOnlyErrorType>&&, int(const int)>);
+
 constexpr void test_val_types() {
   // Test & overload
   {
diff --git a/libcxx/test/std/utilities/expected/expected.expected/monadic/transform_error.pass.cpp b/libcxx/test/std/utilities/expected/expected.expected/monadic/transform_error.pass.cpp
--- a/libcxx/test/std/utilities/expected/expected.expected/monadic/transform_error.pass.cpp
+++ b/libcxx/test/std/utilities/expected/expected.expected/monadic/transform_error.pass.cpp
@@ -26,6 +26,8 @@
 #include <type_traits>
 #include <utility>
 
+#include "../../types.h"
+
 struct LVal {
   constexpr int operator()(int&) { return 1; }
   int operator()(const int&)  = delete;
@@ -98,11 +100,17 @@
       { std::forward<E>(e).transform_error(std::forward<F>(f)) };
     };
 
+// clang-format off
 // [LWG 3877] https://cplusplus.github.io/LWG/issue3877, check constraint failing but not compile error inside the function body.
 static_assert(!has_transform_error<const std::expected<std::unique_ptr<int>, int>&, int()>);
 static_assert(!has_transform_error<const std::expected<std::unique_ptr<int>, int>&&, int()>);
 
-// clang-format off
+// [LWG 3983] https://cplusplus.github.io/LWG/issue3938, check std::expected monadic ops well-formed with move-only error_type.
+static_assert(has_transform_error<std::expected<int, CopyConstructibleErrorType>&, int(CopyConstructibleErrorType &)>);
+static_assert(has_transform_error<const std::expected<int, CopyConstructibleErrorType>&, int(const CopyConstructibleErrorType &)>);
+static_assert(has_transform_error<std::expected<int, MoveOnlyErrorType>&&, int(MoveOnlyErrorType&&)>);
+static_assert(has_transform_error<const std::expected<int, MoveOnlyErrorType>&&, int(const MoveOnlyErrorType&&)>);
+
 constexpr void test_val_types() {
   // Test & overload
   {
diff --git a/libcxx/test/std/utilities/expected/types.h b/libcxx/test/std/utilities/expected/types.h
--- a/libcxx/test/std/utilities/expected/types.h
+++ b/libcxx/test/std/utilities/expected/types.h
@@ -142,4 +142,18 @@
 
 #endif // TEST_HAS_NO_EXCEPTIONS
 
+struct MoveOnlyErrorType {
+  constexpr MoveOnlyErrorType(int) {}
+  MoveOnlyErrorType(MoveOnlyErrorType&&) {}
+  MoveOnlyErrorType(const MoveOnlyErrorType&&) {}
+  MoveOnlyErrorType(const MoveOnlyErrorType&)            = delete;
+  MoveOnlyErrorType& operator=(const MoveOnlyErrorType&) = delete;
+};
+
+struct CopyConstructibleErrorType {
+  constexpr CopyConstructibleErrorType(int) {}
+  CopyConstructibleErrorType(CopyConstructibleErrorType&) {}
+  CopyConstructibleErrorType(const CopyConstructibleErrorType&) {}
+};
+
 #endif // TEST_STD_UTILITIES_EXPECTED_TYPES_H