diff --git a/e2e/src/main.rs b/e2e/src/main.rs
index 5fd5db889..17d7344ec 100644
--- a/e2e/src/main.rs
+++ b/e2e/src/main.rs
@@ -95,15 +95,15 @@ pub mod tests {
 		Ok(app_extrinsics)
 	}
 
-	async fn query_row(
+	async fn query_rows(
 		rpc: &Rpc<AvailConfig>,
 		rows: &[usize],
 		block_hash: H256,
-	) -> anyhow::Result<Vec<Option<Vec<u8>>>> {
+	) -> anyhow::Result<Vec<Vec<u8>>> {
 		let mut params = RpcParams::new();
 		params.push(rows)?;
 		params.push(Some(block_hash))?;
-		let rows: Vec<Option<Vec<u8>>> = rpc.request("kate_queryRows", params).await?;
+		let rows: Vec<Vec<u8>> = rpc.request("kate_queryRows", params).await?;
 
 		Ok(rows)
 	}
@@ -179,21 +179,17 @@ pub mod tests {
 		assert_eq!(grid.row(0), extended_grid.row(0));
 		assert_eq!(grid.row(0), extended_grid.row(1));
 
-		// RPC call
-		let actual_rows = query_row(rpc, &[0, 1, 2], block_hash).await.unwrap();
+		// RPC call: Querying non existing rows should fail
+		assert!(query_rows(rpc, &[2], block_hash).await.is_err());
 
-		let mut expected_rows: Vec<Option<Vec<u8>>> = Vec::new();
-		let iter = [
-			extended_grid.row(0),
-			extended_grid.row(1),
-			extended_grid.row(2),
-		];
-		for row in iter {
+		// RPC call: Querying existing rows should NOT fail
+		let actual_rows = query_rows(rpc, &[0, 1], block_hash).await.unwrap();
+
+		let mut expected_rows: Vec<Vec<u8>> = Vec::new();
+		for row in [extended_grid.row(0), extended_grid.row(1)] {
 			if let Some(row) = row {
 				let flat_row: Vec<u8> = row.iter().flat_map(|r| r.to_bytes().unwrap()).collect();
-				expected_rows.push(Some(flat_row))
-			} else {
-				expected_rows.push(None);
+				expected_rows.push(flat_row);
 			}
 		}
 
diff --git a/examples/deno/api_options.ts b/examples/deno/api_options.ts
index 2f3aae9a1..3a7203bce 100644
--- a/examples/deno/api_options.ts
+++ b/examples/deno/api_options.ts
@@ -69,7 +69,7 @@ export const API_RPC = {
                     isOptional: true
                 }
             ],
-            type: 'Vec<Option<Vec<u8>>>',
+            type: 'Vec<Vec<u8>>',
         }
     }
 }
@@ -87,12 +87,12 @@ export const API_TYPES = {
     KateCommitment: {
         rows: 'Compact<u16>',
         cols: 'Compact<u16>',
-        dataRoot: 'H256',
-        commitment: 'Vec<u8>'
+        commitment: 'Vec<u8>',
+        dataRoot: 'H256'
     },
     V1HeaderExtension: {
-        commitment: 'KateCommitment',
-        appLookup: 'DataLookup'
+        appLookup: 'DataLookup',
+        commitment: 'KateCommitment'
     },
     VTHeaderExtension: {
         newField: 'Vec<u8>',
diff --git a/examples/ts/README.md b/examples/ts/README.md
index 9a333a91b..2309d3905 100644
--- a/examples/ts/README.md
+++ b/examples/ts/README.md
@@ -69,7 +69,7 @@ export default {
     ```
 - Query application data returns data fot the given application id and block hash.
     ```
-    ts-node ts-node query_app_data.ts
+    ts-node query_app_data.ts
     ```
 - Creation of app_id
     ```
@@ -78,7 +78,7 @@ export default {
   Here `i` is the app_id that we would like to create(default is 1).
 - Submit a proposal using the council.
     ```
-    ts-node ts-node submit_proposal.ts
+    ts-node submit_proposal.ts
     ```
 You can also use yarn commands to run the scripts. For example 
 - Start by building the project:
diff --git a/rpc/kate-rpc/src/lib.rs b/rpc/kate-rpc/src/lib.rs
index cf234bec0..bb08a1ca4 100644
--- a/rpc/kate-rpc/src/lib.rs
+++ b/rpc/kate-rpc/src/lib.rs
@@ -43,7 +43,7 @@ where
 		&self,
 		rows: Vec<u32>,
 		at: Option<HashOf<Block>>,
-	) -> RpcResult<Vec<Option<Vec<u8>>>>;
+	) -> RpcResult<Vec<Vec<u8>>>;
 
 	#[method(name = "kate_queryAppData")]
 	async fn query_app_data(
@@ -271,22 +271,24 @@ where
 		&self,
 		rows: Vec<u32>,
 		at: Option<HashOf<Block>>,
-	) -> RpcResult<Vec<Option<Vec<u8>>>> {
+	) -> RpcResult<Vec<Vec<u8>>> {
 		let signed_block = self.get_signed_and_finalized_block(at)?;
 		let evals = self.get_eval_grid(&signed_block).await?;
 
-		let rows: Vec<Option<Vec<u8>>> = rows
-			.iter()
-			.map(|i| {
-				evals.row(*i as usize).map(|row| {
-					row.iter()
-						.flat_map(|a| a.to_bytes().expect("Ser cannot fail"))
-						.collect::<Vec<u8>>()
-				})
-			})
-			.collect();
+		let mut data_rows = Vec::with_capacity(rows.len());
+		for index in rows {
+			let Some(data) = evals.row(index as usize) else {
+				return Err(internal_err!("Non existing row: {:?}", index));
+			};
+			let data: Vec<u8> = data
+				.iter()
+				.flat_map(|a| a.to_bytes().expect("Ser cannot fail"))
+				.collect();
+
+			data_rows.push(data);
+		}
 
-		Ok(rows)
+		Ok(data_rows)
 	}
 
 	async fn query_app_data(