diff --git a/jsonrpc/backend/block.go b/jsonrpc/backend/block.go
index 46bc3b7..5c4e474 100644
--- a/jsonrpc/backend/block.go
+++ b/jsonrpc/backend/block.go
@@ -13,12 +13,7 @@ import (
 )
 
 func (b *JSONRPCBackend) BlockNumber() (hexutil.Uint64, error) {
-	res, err := b.clientCtx.Client.Status(b.ctx)
-	if err != nil {
-		return 0, err
-	}
-
-	return hexutil.Uint64(res.SyncInfo.LatestBlockHeight), nil
+	return hexutil.Uint64(b.app.LastBlockHeight()), nil
 }
 
 func (b *JSONRPCBackend) resolveBlockNrOrHash(blockNrOrHash rpc.BlockNumberOrHash) (uint64, error) {
@@ -72,7 +67,7 @@ func (b *JSONRPCBackend) GetHeaderByNumber(ethBlockNum rpc.BlockNumber) (*corety
 		return nil, nil
 	} else if err != nil {
 		b.logger.Error("failed to get block header by number", "err", err)
-		return nil, err
+		return nil, NewInternalError("failed to get block header by number")
 	}
 
 	// cache the header
@@ -138,7 +133,8 @@ func (b *JSONRPCBackend) blockNumberByHash(hash common.Hash) (uint64, error) {
 
 	number, err := b.app.EVMIndexer().BlockHashToNumber(queryCtx, hash)
 	if err != nil {
-		return 0, err
+		b.logger.Error("failed to get block number by hash", "err", err)
+		return 0, NewInternalError("failed to get block number by hash")
 	}
 
 	_ = b.blockHashCache.Add(hash, number)
diff --git a/jsonrpc/backend/cosmos.go b/jsonrpc/backend/cosmos.go
index fa4fe9a..5598d99 100644
--- a/jsonrpc/backend/cosmos.go
+++ b/jsonrpc/backend/cosmos.go
@@ -17,6 +17,9 @@ func (b *JSONRPCBackend) CosmosTxHashByTxHash(hash common.Hash) ([]byte, error)
 	cosmosTxHash, err := b.app.EVMIndexer().CosmosTxHashByTxHash(queryCtx, hash)
 	if err != nil && errors.Is(err, collections.ErrNotFound) {
 		return nil, nil
+	} else if err != nil {
+		b.logger.Error("failed to get cosmos tx hash by tx hash", "err", err)
+		return nil, NewInternalError("failed to get cosmos tx hash by tx hash")
 	}
 
 	return cosmosTxHash, nil
@@ -32,6 +35,9 @@ func (b *JSONRPCBackend) TxHashByCosmosTxHash(hash []byte) (common.Hash, error)
 	txHash, err := b.app.EVMIndexer().TxHashByCosmosTxHash(queryCtx, hash)
 	if err != nil && errors.Is(err, collections.ErrNotFound) {
 		return common.Hash{}, nil
+	} else if err != nil {
+		b.logger.Debug("failed to get tx hash by cosmos tx hash", "err", err)
+		return common.Hash{}, NewInternalError("failed to get tx hash by cosmos tx hash")
 	}
 
 	return txHash, nil
diff --git a/jsonrpc/backend/filters.go b/jsonrpc/backend/filters.go
index cd3b178..31f5d2e 100644
--- a/jsonrpc/backend/filters.go
+++ b/jsonrpc/backend/filters.go
@@ -27,7 +27,7 @@ func (b *JSONRPCBackend) GetLogsByHeight(height uint64) ([]*coretypes.Log, error
 		return nil, err
 	}
 	if len(txs) != len(receipts) {
-		return nil, NewInternalError("number of transactions and receipts do not match")
+		return nil, NewInternalError("mismatched number of transactions and receipts")
 	}
 
 	blockLogs := []*coretypes.Log{}
diff --git a/jsonrpc/backend/tx.go b/jsonrpc/backend/tx.go
index 43d8e59..5902466 100644
--- a/jsonrpc/backend/tx.go
+++ b/jsonrpc/backend/tx.go
@@ -218,6 +218,10 @@ func (b *JSONRPCBackend) GetTransactionByBlockNumberAndIndex(blockNum rpc.BlockN
 		return nil, err
 	}
 	if txs, ok := b.blockTxsCache.Get(blockNumber); ok {
+		if int(idx) >= len(txs) {
+			return nil, nil
+		}
+
 		return txs[idx], nil
 	}
 
@@ -231,7 +235,7 @@ func (b *JSONRPCBackend) GetTransactionByBlockNumberAndIndex(blockNum rpc.BlockN
 		return nil, nil
 	} else if err != nil {
 		b.logger.Error("failed to get transaction by block and index", "err", err)
-		return nil, err
+		return nil, NewInternalError("failed to get transaction by block and index")
 	}
 
 	return b.getTransaction(txhash)
@@ -265,16 +269,7 @@ func (b *JSONRPCBackend) GetBlockTransactionCountByNumber(blockNum rpc.BlockNumb
 
 // GetRawTransactionByHash returns the bytes of the transaction for the given hash.
 func (b *JSONRPCBackend) GetRawTransactionByHash(hash common.Hash) (hexutil.Bytes, error) {
-	if tx, ok := b.txLookupCache.Get(hash); ok {
-		return tx.ToTransaction().MarshalBinary()
-	}
-
-	queryCtx, err := b.getQueryCtx()
-	if err != nil {
-		return nil, err
-	}
-
-	rpcTx, err := b.app.EVMIndexer().TxByHash(queryCtx, hash)
+	rpcTx, err := b.getTransaction(hash)
 	if err != nil && errors.Is(err, collections.ErrNotFound) {
 		return nil, nil
 	} else if err != nil {
@@ -284,7 +279,6 @@ func (b *JSONRPCBackend) GetRawTransactionByHash(hash common.Hash) (hexutil.Byte
 		return nil, nil
 	}
 
-	_ = b.txLookupCache.Add(hash, rpcTx)
 	return rpcTx.ToTransaction().MarshalBinary()
 }
 
@@ -364,7 +358,7 @@ func (b *JSONRPCBackend) GetBlockReceipts(ctx context.Context, blockNrOrHash rpc
 	}
 
 	if len(txs) != len(receipts) {
-		return nil, fmt.Errorf("receipts length mismatch: %d vs %d", len(txs), len(receipts))
+		return nil, NewInternalError("mismatched number of transactions and receipts")
 	}
 
 	result := make([]map[string]interface{}, len(receipts))
@@ -399,7 +393,7 @@ func (b *JSONRPCBackend) getTransaction(hash common.Hash) (*rpctypes.RPCTransact
 		return nil, nil
 	} else if err != nil {
 		b.logger.Error("failed to get transaction by hash", "err", err)
-		return nil, NewTxIndexingError()
+		return nil, NewInternalError("failed to get transaction by hash")
 	}
 
 	_ = b.txLookupCache.Add(hash, tx)
@@ -421,7 +415,7 @@ func (b *JSONRPCBackend) getReceipt(hash common.Hash) (*coretypes.Receipt, error
 		return nil, nil
 	} else if err != nil {
 		b.logger.Error("failed to get transaction receipt by hash", "err", err)
-		return nil, NewTxIndexingError()
+		return nil, NewInternalError("failed to get transaction receipt by hash")
 	}
 
 	_ = b.receiptCache.Add(hash, receipt)
@@ -444,7 +438,8 @@ func (b *JSONRPCBackend) getBlockTransactions(blockNumber uint64) ([]*rpctypes.R
 		return false, nil
 	})
 	if err != nil {
-		return nil, err
+		b.logger.Error("failed to get block transactions", "err", err)
+		return nil, NewInternalError("failed to get block transactions")
 	}
 
 	// cache the transactions
@@ -468,7 +463,8 @@ func (b *JSONRPCBackend) getBlockReceipts(blockNumber uint64) ([]*coretypes.Rece
 		return false, nil
 	})
 	if err != nil {
-		return nil, err
+		b.logger.Error("failed to get block receipts", "err", err)
+		return nil, NewInternalError("failed to get block receipts")
 	}
 
 	// cache the receipts
diff --git a/jsonrpc/config/config.go b/jsonrpc/config/config.go
index 400d1af..ed9f254 100644
--- a/jsonrpc/config/config.go
+++ b/jsonrpc/config/config.go
@@ -24,8 +24,6 @@ const (
 	// DefaultMaxOpenConnections is the default maximum number of simultaneous connections
 	// for the server listener.
 	DefaultMaxOpenConnections = 100
-	// DefaultLogsCap is the default max number of results can be returned from single `eth_getLogs` query.
-	DefaultLogsCap int32 = 100
 	// DefaultAddress defines the default HTTP server to listen on.
 	DefaultAddress = "127.0.0.1:8545"
 	// DefaultAddressWS defines the default WebSocket server address to bind to.
@@ -58,7 +56,6 @@ const (
 	flagJSONRPCAddressWS            = "json-rpc.address-ws"
 	flagJSONRPCEnableUnsafeCORS     = "json-rpc.enable-unsafe-cors"
 	flagJSONRPCAPIs                 = "json-rpc.apis"
-	flagJSONRPCLogsCap              = "json-rpc.logs-cap"
 	flagJSONRPCHTTPTimeout          = "json-rpc.http-timeout"
 	flagJSONRPCHTTPIdleTimeout      = "json-rpc.http-idle-timeout"
 	flagJSONRPCMaxOpenConnections   = "json-rpc.max-open-connections"
@@ -114,7 +111,7 @@ func DefaultJSONRPCConfig() JSONRPCConfig {
 	return JSONRPCConfig{
 		Enable:           DefaultEnable,
 		Address:          DefaultAddress,
-		EnableWS:         DefaultEnable,
+		EnableWS:         DefaultEnableWS,
 		AddressWS:        DefaultAddressWS,
 		EnableUnsafeCORS: DefaultEnableUnsafeCORS,