diff --git a/cmd/faucet/src/faucet.rs b/cmd/faucet/src/faucet.rs
index 947c5e7230..915a4300af 100644
--- a/cmd/faucet/src/faucet.rs
+++ b/cmd/faucet/src/faucet.rs
@@ -1,7 +1,7 @@
 // Copyright (c) The Starcoin Core Contributors
 // SPDX-License-Identifier: Apache-2.0
 
-use anyhow::{format_err, Result};
+use anyhow::Result;
 use starcoin_account_api::AccountInfo;
 use starcoin_crypto::HashValue;
 use starcoin_logger::prelude::*;
@@ -63,12 +63,6 @@ impl Faucet {
                 let chain_state_reader = self.client.state_reader(StateRootOption::Latest)?;
                 chain_state_reader
                     .get_account_resource(*self.faucet_account.address())?
-                    .ok_or_else(|| {
-                        format_err!(
-                            "Can not find account on chain by address:{}",
-                            self.faucet_account.address()
-                        )
-                    })?
                     .sequence_number()
             }
         };
diff --git a/cmd/tx-factory/src/main.rs b/cmd/tx-factory/src/main.rs
index f2606c14bc..9eca1eeb98 100644
--- a/cmd/tx-factory/src/main.rs
+++ b/cmd/tx-factory/src/main.rs
@@ -96,11 +96,11 @@ fn get_account_or_default(
 
             let addr = default_account.clone().unwrap().address;
             let state_reader = client.state_reader(StateRootOption::Latest)?;
-            let mut balance = state_reader.get_balance(addr)?;
+            let mut balance = state_reader.get_balance(addr);
             // balance resource has not been created
-            while balance.is_none() {
+            while balance.is_err() {
                 std::thread::sleep(Duration::from_millis(1000));
-                balance = state_reader.get_balance(addr)?;
+                balance = state_reader.get_balance(addr);
                 info!("account balance is null.");
             }
             default_account.unwrap()
@@ -228,8 +228,8 @@ impl TxnMocker {
     ) -> Result<Self> {
         let state_reader = client.state_reader(StateRootOption::Latest)?;
 
-        let account_resource = state_reader.get_account_resource(account_address)?;
-        if account_resource.is_none() {
+        let account_resource = state_reader.get_account_resource(account_address);
+        if account_resource.is_err() {
             bail!("account {} not exists, please faucet it", account_address);
         }
         let account_resource = account_resource.unwrap();
@@ -277,8 +277,8 @@ impl TxnMocker {
             None => {
                 let state_reader = self.client.state_reader(StateRootOption::Latest)?;
 
-                let account_resource = state_reader.get_account_resource(self.account_address)?;
-                if account_resource.is_none() {
+                let account_resource = state_reader.get_account_resource(self.account_address);
+                if account_resource.is_err() {
                     bail!(
                         "account {} not exists, please faucet it",
                         &self.account_address
diff --git a/network-rpc/api/src/lib.rs b/network-rpc/api/src/lib.rs
index 225f039bda..b4682f822a 100644
--- a/network-rpc/api/src/lib.rs
+++ b/network-rpc/api/src/lib.rs
@@ -271,7 +271,7 @@ pub trait NetworkRpc: Sized + Send + Sync + 'static {
         &self,
         peer_id: PeerId,
         req: GetAccountState,
-    ) -> BoxFuture<Result<Option<AccountState>>>;
+    ) -> BoxFuture<Result<AccountState>>;
 
     fn get_block_ids(&self, peer_id: PeerId, req: GetBlockIds)
         -> BoxFuture<Result<Vec<HashValue>>>;
@@ -292,7 +292,7 @@ pub trait NetworkRpc: Sized + Send + Sync + 'static {
         &self,
         peer_id: PeerId,
         request: GetTableInfo,
-    ) -> BoxFuture<Result<Option<TableInfo>>>;
+    ) -> BoxFuture<Result<TableInfo>>;
 
     fn get_dag_block_children(
         &self,
diff --git a/network-rpc/api/src/remote_chain_state.rs b/network-rpc/api/src/remote_chain_state.rs
index a3f70d7dc2..a7c5946953 100644
--- a/network-rpc/api/src/remote_chain_state.rs
+++ b/network-rpc/api/src/remote_chain_state.rs
@@ -70,7 +70,7 @@ impl ChainStateReader for RemoteChainStateReader {
         Ok(state_proof)
     }
 
-    fn get_account_state(&self, account_address: &AccountAddress) -> Result<Option<AccountState>> {
+    fn get_account_state(&self, account_address: &AccountAddress) -> Result<AccountState> {
         //TODO: How to verify it
         let peer_id = self
             .peer_id
@@ -135,9 +135,8 @@ impl ChainStateReader for RemoteChainStateReader {
             .ok_or_else(|| anyhow!("peer id not set"))?;
         let req = GetTableInfo(address);
         let client = self.client.clone();
-        let table_info: Option<TableInfo> =
-            futures::executor::block_on(client.get_state_table_info(peer_id, req))?;
-        Ok(table_info)
+        let table_info = futures::executor::block_on(client.get_state_table_info(peer_id, req))?;
+        Ok(Some(table_info))
     }
 }
 
diff --git a/network-rpc/src/rpc.rs b/network-rpc/src/rpc.rs
index 5aa6d4e9a6..d295b29cdb 100644
--- a/network-rpc/src/rpc.rs
+++ b/network-rpc/src/rpc.rs
@@ -226,15 +226,18 @@ impl gen_server::NetworkRpc for NetworkRpcImpl {
     fn get_state_with_proof(
         &self,
         _peer_id: PeerId,
-        req: GetStateWithProof,
+        _req: GetStateWithProof,
     ) -> BoxFuture<Result<StateWithProof>> {
+        // XXX FIXME YSG
+        /*
         let state_service = self.state_service.clone();
         let fut = async move {
             state_service
                 .get_with_proof_by_root(req.access_path, req.state_root)
                 .await
         };
-        Box::pin(fut)
+        Box::pin(fut) */
+        unimplemented!("")
     }
 
     fn get_state_with_table_item_proof(
@@ -255,7 +258,7 @@ impl gen_server::NetworkRpc for NetworkRpcImpl {
         &self,
         _peer_id: PeerId,
         request: GetTableInfo,
-    ) -> BoxFuture<Result<Option<TableInfo>>> {
+    ) -> BoxFuture<Result<TableInfo>> {
         let state_service = self.state_service.clone();
         let fut = async move { state_service.get_table_info(request.0).await };
         Box::pin(fut)
@@ -265,7 +268,7 @@ impl gen_server::NetworkRpc for NetworkRpcImpl {
         &self,
         _peer_id: PeerId,
         req: GetAccountState,
-    ) -> BoxFuture<Result<Option<AccountState>>> {
+    ) -> BoxFuture<Result<AccountState>> {
         let state_service = self.state_service.clone();
         let fut = async move {
             state_service
diff --git a/rpc/client/src/remote_state_reader.rs b/rpc/client/src/remote_state_reader.rs
index 6ae0cdc335..62c85984a4 100644
--- a/rpc/client/src/remote_state_reader.rs
+++ b/rpc/client/src/remote_state_reader.rs
@@ -79,7 +79,7 @@ impl<'a> ChainStateReader for RemoteStateReader<'a> {
             .map(Into::into)
     }
 
-    fn get_account_state(&self, _address: &AccountAddress) -> Result<Option<AccountState>> {
+    fn get_account_state(&self, _address: &AccountAddress) -> Result<AccountState> {
         unimplemented!()
         //TODO implement get_account_state by root
     }
diff --git a/rpc/server/src/module/chain_rpc.rs b/rpc/server/src/module/chain_rpc.rs
index dedee3b0e6..5257c7fe14 100644
--- a/rpc/server/src/module/chain_rpc.rs
+++ b/rpc/server/src/module/chain_rpc.rs
@@ -21,7 +21,7 @@ use starcoin_rpc_api::types::{
     TransactionInfoWithProofView, TransactionView,
 };
 use starcoin_rpc_api::FutureResult;
-use starcoin_state_api::StateView;
+use starcoin_vm_types::StateView;
 use starcoin_statedb::ChainStateDB;
 use starcoin_storage::Storage;
 use starcoin_types::access_path::AccessPath;
diff --git a/rpc/server/src/module/contract_rpc.rs b/rpc/server/src/module/contract_rpc.rs
index eee55e3578..aed1db5d3f 100644
--- a/rpc/server/src/module/contract_rpc.rs
+++ b/rpc/server/src/module/contract_rpc.rs
@@ -31,7 +31,7 @@ use starcoin_types::language_storage::{ModuleId, StructTag};
 use starcoin_types::transaction::{DryRunTransaction, RawUserTransaction, TransactionPayload};
 use starcoin_vm_types::access_path::AccessPath;
 use starcoin_vm_types::file_format::CompiledModule;
-use starcoin_vm_types::state_view::StateView;
+use starcoin_vm_types::state_store::StateView;
 use starcoin_vm_types::transaction::authenticator::AccountPublicKey;
 use std::str::FromStr;
 use std::sync::Arc;
diff --git a/state/api/src/chain_state.rs b/state/api/src/chain_state.rs
index 5803fc7139..fac085f114 100644
--- a/state/api/src/chain_state.rs
+++ b/state/api/src/chain_state.rs
@@ -116,13 +116,13 @@ pub trait ChainStateReader: StateView {
     fn get_with_proof(&self, access_path: &AccessPath) -> Result<StateWithProof>;
 
     /// Gets account state
-    fn get_account_state(&self, address: &AccountAddress) -> Result<Option<AccountState>>;
+    fn get_account_state(&self, address: &AccountAddress) -> Result<AccountState>;
 
     /// get whole state data of some account address.
     fn get_account_state_set(&self, address: &AccountAddress) -> Result<Option<AccountStateSet>>;
 
     fn exist_account(&self, address: &AccountAddress) -> Result<bool> {
-        self.get_account_state(address).map(|state| state.is_some())
+        Ok(self.get_account_state(address).is_ok())
     }
 
     /// Gets current state root.
diff --git a/state/service/src/service.rs b/state/service/src/service.rs
index 1a18a7dc11..8976591042 100644
--- a/state/service/src/service.rs
+++ b/state/service/src/service.rs
@@ -97,7 +97,7 @@ impl ServiceHandler<Self, StateRequest> for ChainStateService {
                 StateResponse::StateWithProof(Box::new(self.service.get_with_proof(access_path)?))
             }
             StateRequest::GetAccountState(address) => {
-                StateResponse::AccountState(self.service.get_account_state(&address)?)
+                StateResponse::AccountState(Option::from(self.service.get_account_state(&address)?))
             }
             StateRequest::StateRoot() => StateResponse::StateRoot(self.service.state_root()),
             StateRequest::GetWithProofByRoot(state_key, state_root) => {
@@ -113,10 +113,10 @@ impl ServiceHandler<Self, StateRequest> for ChainStateService {
                 ))
             }
             StateRequest::GetAccountStateByRoot(account, state_root) => {
-                StateResponse::AccountState(
+                StateResponse::AccountState(Some(
                     self.service
                         .get_account_state_by_root(account, state_root)?,
-                )
+                ))
             }
             StateRequest::GetAccountStateSet {
                 address,
@@ -207,7 +207,7 @@ impl Inner {
         &self,
         account: AccountAddress,
         state_root: HashValue,
-    ) -> Result<Option<AccountState>> {
+    ) -> Result<AccountState> {
         let reader = self.state_db.fork_at(state_root);
         reader.get_account_state(&account)
     }
@@ -234,7 +234,7 @@ impl ChainStateReader for Inner {
         self.state_db.get_with_proof(access_path)
     }
 
-    fn get_account_state(&self, address: &AccountAddress) -> Result<Option<AccountState>> {
+    fn get_account_state(&self, address: &AccountAddress) -> Result<AccountState> {
         self.state_db.get_account_state(address)
     }
     fn get_account_state_set(&self, address: &AccountAddress) -> Result<Option<AccountStateSet>> {
diff --git a/state/statedb/src/lib.rs b/state/statedb/src/lib.rs
index 513ce2516f..21d4df4f26 100644
--- a/state/statedb/src/lib.rs
+++ b/state/statedb/src/lib.rs
@@ -485,10 +485,12 @@ impl ChainStateReader for ChainStateDB {
         Ok(state_with_proof)
     }
 
-    fn get_account_state(&self, address: &AccountAddress) -> Result<Option<AccountState>> {
-        Ok(self
-            .get_account_state_object_option(address)?
-            .map(|state_object| state_object.to_state()))
+    fn get_account_state(&self, address: &AccountAddress) -> Result<AccountState> {
+        let account_state = self.get_account_state_object_option(address)?;
+        match account_state {
+            Some(account_state) => Ok(account_state.to_state()),
+            None => Err(AccountNotExist(*address).into()),
+        }
     }
 
     fn get_account_state_set(&self, address: &AccountAddress) -> Result<Option<AccountStateSet>> {
diff --git a/txpool/src/pool_client.rs b/txpool/src/pool_client.rs
index 450520e3e9..6f95fcb55b 100644
--- a/txpool/src/pool_client.rs
+++ b/txpool/src/pool_client.rs
@@ -82,9 +82,7 @@ impl CachedSeqNumberClient {
                 );
                 0
             }
-            Ok(account_resource) => account_resource
-                .map(|res| res.sequence_number())
-                .unwrap_or_default(),
+            Ok(account_resource) => account_resource.sequence_number(),
         }
     }
 }