diff --git a/serviceerror/convert.go b/serviceerror/convert.go
index 011f3a9b..55222660 100644
--- a/serviceerror/convert.go
+++ b/serviceerror/convert.go
@@ -100,7 +100,12 @@ func FromStatus(st *status.Status) error {
 	case codes.Canceled:
 		return newCanceled(st)
 	case codes.Unavailable:
-		return newUnavailable(st)
+		switch errDetails := errDetails.(type) {
+		case *errordetails.NamespaceUnavailableFailure:
+			return newNamespaceUnavailable(st, errDetails)
+		default:
+			return newUnavailable(st)
+		}
 	case codes.Unimplemented:
 		return newUnimplemented(st)
 	case codes.Unknown:
diff --git a/serviceerror/namespace_unavailable.go b/serviceerror/namespace_unavailable.go
new file mode 100644
index 00000000..963a5efc
--- /dev/null
+++ b/serviceerror/namespace_unavailable.go
@@ -0,0 +1,81 @@
+// The MIT License
+//
+// Copyright (c) 2024 Temporal Technologies Inc.  All rights reserved.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package serviceerror
+
+import (
+	"fmt"
+
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+
+	"go.temporal.io/api/errordetails/v1"
+)
+
+type (
+	// NamespaceUnavailable is returned by the service when a request addresses a namespace that is unavailable. For
+	// example, when a namespace is in the process of failing over between clusters. This is a transient error that
+	// should be automatically retried by clients.
+	NamespaceUnavailable struct {
+		Namespace string
+		st        *status.Status
+	}
+)
+
+// NewNamespaceUnavailable returns new NamespaceUnavailable error.
+func NewNamespaceUnavailable(namespace string) error {
+	return &NamespaceUnavailable{
+		Namespace: namespace,
+	}
+}
+
+// Error returns string message.
+func (e *NamespaceUnavailable) Error() string {
+	// No need to do a nil check, that's handled in Message().
+	if e.st.Message() != "" {
+		return e.st.Message()
+	}
+	// Continuing the practice of starting errors with upper case and ending with periods even if it's not
+	// idiomatic.
+	return fmt.Sprintf("Namespace unavailable: %q.", e.Namespace)
+}
+
+func (e *NamespaceUnavailable) Status() *status.Status {
+	if e.st != nil {
+		return e.st
+	}
+	st := status.New(codes.Unavailable, e.Error())
+	// We seem to be okay ignoring these errors everywhere else, doing this here too.
+	st, _ = st.WithDetails(
+		&errordetails.NamespaceUnavailableFailure{
+			Namespace: e.Namespace,
+		},
+	)
+	return st
+}
+
+func newNamespaceUnavailable(st *status.Status, errDetails *errordetails.NamespaceUnavailableFailure) error {
+	return &NamespaceUnavailable{
+		st:        st,
+		Namespace: errDetails.GetNamespace(),
+	}
+}