diff --git a/pkg/neorpc/errors.go b/pkg/neorpc/errors.go
index d6488283a..b38d0b695 100644
--- a/pkg/neorpc/errors.go
+++ b/pkg/neorpc/errors.go
@@ -282,13 +282,13 @@ func NewError(code int64, message string, data string) *Error {
 // NewParseError creates a new error with code
 // -32700.
 func NewParseError(data string) *Error {
-	return NewError(BadRequestCode, "Parse Error", data)
+	return NewError(BadRequestCode, "Parse error", data)
 }
 
 // NewInvalidRequestError creates a new error with
 // code -32600.
 func NewInvalidRequestError(data string) *Error {
-	return NewError(InvalidRequestCode, "Invalid Request", data)
+	return NewError(InvalidRequestCode, "Invalid request", data)
 }
 
 // NewMethodNotFoundError creates a new error with
@@ -300,7 +300,7 @@ func NewMethodNotFoundError(data string) *Error {
 // NewInvalidParamsError creates a new error with
 // code -32602.
 func NewInvalidParamsError(data string) *Error {
-	return NewError(InvalidParamsCode, "Invalid Params", data)
+	return NewError(InvalidParamsCode, "Invalid params", data)
 }
 
 // NewInternalServerError creates a new error with
diff --git a/pkg/rpcclient/rpc_test.go b/pkg/rpcclient/rpc_test.go
index d36d6804c..32d8d9ca8 100644
--- a/pkg/rpcclient/rpc_test.go
+++ b/pkg/rpcclient/rpc_test.go
@@ -1456,7 +1456,7 @@ var rpcClientErrorCases = map[string][]rpcClientErrorCase{
 			},
 		},
 	},
-	`{"id":1,"jsonrpc":"2.0","error":{"code":-32602,"message":"Invalid Params"}}`: {
+	`{"id":1,"jsonrpc":"2.0","error":{"code":-32602,"message":"Invalid params"}}`: {
 		{
 			name: "getapplicationlog_invalid_params_error",
 			invoke: func(c *Client) (any, error) {
diff --git a/pkg/rpcclient/wsclient_test.go b/pkg/rpcclient/wsclient_test.go
index af2b65d1b..e004659f3 100644
--- a/pkg/rpcclient/wsclient_test.go
+++ b/pkg/rpcclient/wsclient_test.go
@@ -83,7 +83,7 @@ func TestWSClientSubscription(t *testing.T) {
 	t.Run("bad", func(t *testing.T) {
 		for name, f := range cases {
 			t.Run(name, func(t *testing.T) {
-				srv := initTestServer(t, `{"jsonrpc": "2.0", "id": 1, "error":{"code":-32602,"message":"Invalid Params"}}`)
+				srv := initTestServer(t, `{"jsonrpc": "2.0", "id": 1, "error":{"code":-32602,"message":"Invalid params"}}`)
 				wsc, err := NewWS(context.TODO(), httpURLtoWS(srv.URL), WSOptions{})
 				require.NoError(t, err)
 				wsc.getNextRequestID = getTestRequestID
@@ -118,7 +118,7 @@ func TestWSClientUnsubscription(t *testing.T) {
 			err := wsc.Unsubscribe("0")
 			require.Error(t, err)
 		}},
-		"error returned": {`{"jsonrpc": "2.0", "id": 1, "error":{"code":-32602,"message":"Invalid Params"}}`, func(t *testing.T, wsc *WSClient) {
+		"error returned": {`{"jsonrpc": "2.0", "id": 1, "error":{"code":-32602,"message":"Invalid params"}}`, func(t *testing.T, wsc *WSClient) {
 			// We can't really subscribe using this stub server, so set up wsc internals.
 			wsc.subscriptions["0"] = &blockReceiver{}
 			err := wsc.Unsubscribe("0")
diff --git a/pkg/services/rpcsrv/server_test.go b/pkg/services/rpcsrv/server_test.go
index 66393c11c..441abcf1f 100644
--- a/pkg/services/rpcsrv/server_test.go
+++ b/pkg/services/rpcsrv/server_test.go
@@ -3148,15 +3148,15 @@ func testRPCProtocol(t *testing.T, doRPCCall func(string, string, *testing.T) []
 	t.Run("calculatenetworkfee", func(t *testing.T) {
 		t.Run("no parameters", func(t *testing.T) {
 			body := doRPCCall(`{"jsonrpc": "2.0", "id": 1, "method": "calculatenetworkfee", "params": []}"`, httpSrv.URL, t)
-			_ = checkErrGetResult(t, body, true, neorpc.InvalidParamsCode, "Invalid Params")
+			_ = checkErrGetResult(t, body, true, neorpc.InvalidParamsCode, "Invalid params")
 		})
 		t.Run("non-base64 parameter", func(t *testing.T) {
 			body := doRPCCall(`{"jsonrpc": "2.0", "id": 1, "method": "calculatenetworkfee", "params": ["noatbase64"]}"`, httpSrv.URL, t)
-			_ = checkErrGetResult(t, body, true, neorpc.InvalidParamsCode, "Invalid Params")
+			_ = checkErrGetResult(t, body, true, neorpc.InvalidParamsCode, "Invalid params")
 		})
 		t.Run("non-transaction parameter", func(t *testing.T) {
 			body := doRPCCall(`{"jsonrpc": "2.0", "id": 1, "method": "calculatenetworkfee", "params": ["bm90IGEgdHJhbnNhY3Rpb24K"]}"`, httpSrv.URL, t)
-			_ = checkErrGetResult(t, body, true, neorpc.InvalidParamsCode, "Invalid Params")
+			_ = checkErrGetResult(t, body, true, neorpc.InvalidParamsCode, "Invalid params")
 		})
 		calcReq := func(t *testing.T, tx *transaction.Transaction) []byte {
 			rpc := fmt.Sprintf(`{"jsonrpc": "2.0", "id": 1, "method": "calculatenetworkfee", "params": ["%s"]}"`, base64.StdEncoding.EncodeToString(tx.Bytes()))