diff --git a/Cargo.lock b/Cargo.lock
index 27361705..8f764512 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -4233,9 +4233,9 @@ dependencies = [
 
 [[package]]
 name = "ismp-parachain-inherent"
-version = "1.6.2"
+version = "1.6.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "01640c48d57c367289df9d4e60ff838569ff7fd7efa7807f28fa0ec01eb6bf42"
+checksum = "1d14a368b3bac5430c081e386d732f463d3c6af47541a29a02eaacd1ea71053d"
 dependencies = [
  "anyhow",
  "async-trait",
diff --git a/pallets/regions/src/lib.rs b/pallets/regions/src/lib.rs
index e0eb431c..88b8ba9d 100644
--- a/pallets/regions/src/lib.rs
+++ b/pallets/regions/src/lib.rs
@@ -153,6 +153,8 @@ pub mod pallet {
 		NotUnavailable,
 		/// The given region id is not valid.
 		InvalidRegionId,
+		/// Failed to get the latest height of the Coretime chain.
+		LatestHeightInaccessible,
 	}
 
 	#[pallet::call]
@@ -238,10 +240,11 @@ pub mod pallet {
 			let key = [pallet_hash, storage_hash, region_id_hash, region_id_encoded].concat();
 
 			let coretime_chain_height =
-				T::StateMachineHeightProvider::get_latest_state_machine_height(StateMachineId {
+				T::StateMachineHeightProvider::latest_state_machine_height(StateMachineId {
 					state_id: T::CoretimeChain::get(),
 					consensus_state_id: PARACHAIN_CONSENSUS_ID,
-				});
+				})
+				.ok_or(Error::<T>::LatestHeightInaccessible)?;
 
 			// TODO: should requests be coupled in the future?
 			let get = DispatchGet {
diff --git a/pallets/regions/src/mock.rs b/pallets/regions/src/mock.rs
index 07c91acf..58b86b93 100644
--- a/pallets/regions/src/mock.rs
+++ b/pallets/regions/src/mock.rs
@@ -90,8 +90,8 @@ parameter_types! {
 
 pub struct MockStateMachineHeightProvider;
 impl StateMachineHeightProvider for MockStateMachineHeightProvider {
-	fn get_latest_state_machine_height(_id: StateMachineId) -> u64 {
-		0
+	fn latest_state_machine_height(_id: StateMachineId) -> Option<u64> {
+		Some(0)
 	}
 }
 
diff --git a/pallets/regions/src/primitives.rs b/pallets/regions/src/primitives.rs
index 17f251fa..ef046d1c 100644
--- a/pallets/regions/src/primitives.rs
+++ b/pallets/regions/src/primitives.rs
@@ -17,5 +17,5 @@ use ismp::consensus::StateMachineId;
 
 pub trait StateMachineHeightProvider {
 	/// Return the latest height of the state machine
-	fn get_latest_state_machine_height(id: StateMachineId) -> u64;
+	fn latest_state_machine_height(id: StateMachineId) -> Option<u64>;
 }
diff --git a/pallets/regions/src/tests.rs b/pallets/regions/src/tests.rs
index fdf04117..4ee136f6 100644
--- a/pallets/regions/src/tests.rs
+++ b/pallets/regions/src/tests.rs
@@ -277,7 +277,7 @@ fn on_timeout_works() {
 		invalid_get_req.keys.push(vec![0u8; 15]);
 		assert_err!(
 			module.on_timeout(Timeout::Request(Request::Get(invalid_get_req.clone()))),
-			IsmpCustomError::DecodeFailed
+			IsmpCustomError::KeyDecodeFailed
 		);
 
 		// invalid id: region not found
diff --git a/runtime/regionx/src/lib.rs b/runtime/regionx/src/lib.rs
index 5a8c40a6..9e9c4745 100644
--- a/runtime/regionx/src/lib.rs
+++ b/runtime/regionx/src/lib.rs
@@ -596,8 +596,8 @@ impl pallet_collator_selection::Config for Runtime {
 
 pub struct StateMachineHeightProvider;
 impl StateMachineHeightProviderT for StateMachineHeightProvider {
-	fn get_latest_state_machine_height(id: StateMachineId) -> u64 {
-		Ismp::latest_state_machine_height(id).unwrap_or(0) // TODO
+	fn latest_state_machine_height(id: StateMachineId) -> Option<u64> {
+		Ismp::latest_state_machine_height(id)
 	}
 }