fix issue 373 (#964)

* fix issue 373

* Adjustment format

* Adjustment format

* Adjustment format

* change readme

core/src/server/DBWrapper.cpp

@@ -165,7 +165,8 @@ DBWrapper::StartService() {
         db_ = engine::DBFactory::Build(opt);
     } catch (std::exception& ex) {
         std::cerr << "Error: failed to open database: " << ex.what()
-                  << ". Possible reason: the meta system does not work." << std::endl;
+                  << ". Possible reason: Meta Tables schema is damaged "
+                  << "or created by in-compatible Milvus version." << std::endl;
         kill(0, SIGUSR1);
     }