diff --git a/pkg/core/mempool/mem_pool.go b/pkg/core/mempool/mem_pool.go
index 47a9a8723..7e1bb98ef 100644
--- a/pkg/core/mempool/mem_pool.go
+++ b/pkg/core/mempool/mem_pool.go
@@ -22,7 +22,7 @@ var (
 	// ErrConflict is returned when transaction being added is incompatible
 	// with the contents of the memory pool (Sender doesn't have enough GAS
 	// to pay for all transactions in the pool).
-	ErrConflict = errors.New("conflicts with the memory pool")
+	ErrConflict = errors.New("conflicts: insufficient funds for all pooled tx")
 	// ErrDup is returned when transaction being added is already present
 	// in the memory pool.
 	ErrDup = errors.New("already in the memory pool")
diff --git a/pkg/rpc/response/errors.go b/pkg/rpc/response/errors.go
index e19df1166..de0bf4057 100644
--- a/pkg/rpc/response/errors.go
+++ b/pkg/rpc/response/errors.go
@@ -90,6 +90,9 @@ func NewSubmitError(code int64, message string) *Error {
 
 // Error implements the error interface.
 func (e *Error) Error() string {
+	if e.Cause == nil {
+		return fmt.Sprintf("%s (%d) - %s", e.Message, e.Code, e.Data)
+	}
 	return fmt.Sprintf("%s (%d) - %s - %s", e.Message, e.Code, e.Data, e.Cause)
 }