diff --git a/oap-server/server-storage-plugin/storage-elasticsearch-plugin/src/main/java/org/apache/skywalking/oap/server/storage/plugin/elasticsearch/query/MetadataQueryEsDAO.java b/oap-server/server-storage-plugin/storage-elasticsearch-plugin/src/main/java/org/apache/skywalking/oap/server/storage/plugin/elasticsearch/query/MetadataQueryEsDAO.java
index 80ff9a737d5777a45ff6d3198432b77e6932a097..aa4bb8cf519e1e12435558ceb2ee42f33979c6b9 100644
--- a/oap-server/server-storage-plugin/storage-elasticsearch-plugin/src/main/java/org/apache/skywalking/oap/server/storage/plugin/elasticsearch/query/MetadataQueryEsDAO.java
+++ b/oap-server/server-storage-plugin/storage-elasticsearch-plugin/src/main/java/org/apache/skywalking/oap/server/storage/plugin/elasticsearch/query/MetadataQueryEsDAO.java
@@ -197,6 +197,8 @@ public class MetadataQueryEsDAO extends EsDAO implements IMetadataQueryDAO {
                 JsonObject properties = GSON.fromJson(propertiesString, JsonObject.class);
                 if (properties.has(LANGUAGE)) {
                     serviceInstance.setLanguage(LanguageTrans.INSTANCE.value(properties.get(LANGUAGE).getAsString()));
+                } else {
+                    serviceInstance.setLanguage(Language.UNKNOWN);
                 }
 
                 if (properties.has(OS_NAME)) {
diff --git a/oap-server/server-storage-plugin/storage-jdbc-hikaricp-plugin/src/main/java/org/apache/skywalking/oap/server/storage/plugin/jdbc/h2/dao/H2MetadataQueryDAO.java b/oap-server/server-storage-plugin/storage-jdbc-hikaricp-plugin/src/main/java/org/apache/skywalking/oap/server/storage/plugin/jdbc/h2/dao/H2MetadataQueryDAO.java
index 301887f0c4c0fc0d49da04006468f2f30acc6251..e7a1c2a664b0693c20fae0c8d1bc6df41bc0b65f 100644
--- a/oap-server/server-storage-plugin/storage-jdbc-hikaricp-plugin/src/main/java/org/apache/skywalking/oap/server/storage/plugin/jdbc/h2/dao/H2MetadataQueryDAO.java
+++ b/oap-server/server-storage-plugin/storage-jdbc-hikaricp-plugin/src/main/java/org/apache/skywalking/oap/server/storage/plugin/jdbc/h2/dao/H2MetadataQueryDAO.java
@@ -222,6 +222,8 @@ public class H2MetadataQueryDAO implements IMetadataQueryDAO {
                         JsonObject properties = GSON.fromJson(propertiesString, JsonObject.class);
                         if (properties.has(LANGUAGE)) {
                             serviceInstance.setLanguage(LanguageTrans.INSTANCE.value(properties.get(LANGUAGE).getAsString()));
+                        } else {
+                            serviceInstance.setLanguage(Language.UNKNOWN);
                         }
 
                         if (properties.has(OS_NAME)) {