diff --git a/services/identity/src/client_service.rs b/services/identity/src/client_service.rs
--- a/services/identity/src/client_service.rs
+++ b/services/identity/src/client_service.rs
@@ -694,6 +694,17 @@
       redact_sensitive_data(&message.user_id)
     );
 
+    if self
+      .client
+      .get_user_login_flow(&message.user_id)
+      .await?
+      .is_v1_flows()
+    {
+      return Err(tonic::Status::failed_precondition(
+        tonic_status_messages::USE_V1_FLOW,
+      ));
+    }
+
     let user_identifier = self
       .client
       .get_user_identity(&message.user_id)
@@ -779,6 +790,17 @@
     let user_id = message.user_id;
     let device_id = flattened_device_key_upload.device_id_key.clone();
 
+    if self
+      .client
+      .get_user_login_flow(&user_id)
+      .await?
+      .is_v1_flows()
+    {
+      return Err(tonic::Status::failed_precondition(
+        tonic_status_messages::USE_V1_FLOW,
+      ));
+    }
+
     let nonce = challenge_response.verify_and_get_nonce(&device_id)?;
     self.verify_and_remove_nonce(&nonce).await?;
 
diff --git a/services/identity/src/constants.rs b/services/identity/src/constants.rs
--- a/services/identity/src/constants.rs
+++ b/services/identity/src/constants.rs
@@ -241,6 +241,7 @@
   pub const RETRY_FROM_NATIVE: &str = "retry_from_native";
   pub const USER_IS_NOT_STAFF: &str = "user_is_not_staff";
   pub const USE_NEW_FLOW: &str = "use_new_flow";
+  pub const USE_V1_FLOW: &str = "use_v1_flow";
 }
 
 // Tunnelbroker
diff --git a/services/identity/src/grpc_services/authenticated.rs b/services/identity/src/grpc_services/authenticated.rs
--- a/services/identity/src/grpc_services/authenticated.rs
+++ b/services/identity/src/grpc_services/authenticated.rs
@@ -434,6 +434,17 @@
     let (user_id, device_id) = get_user_and_device_id(&request)?;
     let message = request.into_inner();
 
+    if self
+      .db_client
+      .get_user_login_flow(&user_id)
+      .await?
+      .is_v1_flows()
+    {
+      return Err(tonic::Status::failed_precondition(
+        tonic_status_messages::USE_V1_FLOW,
+      ));
+    }
+
     debug!(
       "Primary device logout request for user_id={}, device_id={}",
       user_id, device_id
@@ -502,6 +513,17 @@
   ) -> Result<tonic::Response<Empty>, tonic::Status> {
     let (user_id, device_id) = get_user_and_device_id(&request)?;
 
+    if self
+      .db_client
+      .get_user_login_flow(&user_id)
+      .await?
+      .is_v1_flows()
+    {
+      return Err(tonic::Status::failed_precondition(
+        tonic_status_messages::USE_V1_FLOW,
+      ));
+    }
+
     debug!(
       "Secondary device logout request for user_id={}, device_id={}",
       user_id, device_id