diff --git a/dhp-workflows/dhp-aggregation/src/main/java/eu/dnetlib/dhp/aggregation/mdstore/MDStoreActionNode.java b/dhp-workflows/dhp-aggregation/src/main/java/eu/dnetlib/dhp/aggregation/mdstore/MDStoreActionNode.java
index d4824ed0a..6cb0537b2 100644
--- a/dhp-workflows/dhp-aggregation/src/main/java/eu/dnetlib/dhp/aggregation/mdstore/MDStoreActionNode.java
+++ b/dhp-workflows/dhp-aggregation/src/main/java/eu/dnetlib/dhp/aggregation/mdstore/MDStoreActionNode.java
@@ -38,8 +38,8 @@ public class MDStoreActionNode {
 	public static final String COMMIT_VERSION_URL = "%s/version/%s/commit/%s";
 	public static final String ROLLBACK_VERSION_URL = "%s/version/%s/abort";
 
-	public static final String READ_LOCK_URL = "%s/mdstores/mdstore/%s/startReading";
-	public static final String READ_UNLOCK_URL = "%s/mdstores/version/%s/endReading";
+	public static final String READ_LOCK_URL = "%s/mdstore/%s/startReading";
+	public static final String READ_UNLOCK_URL = "%s/version/%s/endReading";
 
 	private static final String MDSTOREVERSIONPARAM = "mdStoreVersion";
 	private static final String MDSTOREREADLOCKPARAM = "mdStoreReadLockVersion";
@@ -94,11 +94,7 @@ public class MDStoreActionNode {
 				System.setProperty("hadoop.home.dir", "/");
 				// Get the filesystem - HDFS
 				FileSystem fs = FileSystem.get(URI.create(hdfsuri), conf);
-				String mdStoreSizeParam = argumentParser.get("mdStoreSize");
 
-				if (StringUtils.isBlank(mdStoreSizeParam)) {
-					throw new IllegalArgumentException("missing or empty argument mdStoreSize");
-				}
 				Path hdfstoreSizepath = new Path(mdStoreVersion.getHdfsPath() + "/size");
 
 				FSDataInputStream inputStream = fs.open(hdfstoreSizepath);
diff --git a/dhp-workflows/dhp-aggregation/src/test/java/eu/dnetlib/dhp/collection/CollectionJobTest.java b/dhp-workflows/dhp-aggregation/src/test/java/eu/dnetlib/dhp/collection/CollectionJobTest.java
index c3b05f5c9..6f7bb2bc2 100644
--- a/dhp-workflows/dhp-aggregation/src/test/java/eu/dnetlib/dhp/collection/CollectionJobTest.java
+++ b/dhp-workflows/dhp-aggregation/src/test/java/eu/dnetlib/dhp/collection/CollectionJobTest.java
@@ -16,6 +16,8 @@ import org.junit.jupiter.api.io.TempDir;
 
 import com.fasterxml.jackson.databind.ObjectMapper;
 
+import eu.dnetlib.data.mdstore.manager.common.model.MDStoreCurrentVersion;
+import eu.dnetlib.data.mdstore.manager.common.model.MDStoreVersion;
 import eu.dnetlib.dhp.model.mdstore.MetadataRecord;
 import eu.dnetlib.dhp.model.mdstore.Provenance;
 import eu.dnetlib.dhp.schema.common.ModelSupport;
@@ -37,6 +39,17 @@ public class CollectionJobTest {
 		spark.stop();
 	}
 
+	@Test
+	public void testJSONSerialization() throws Exception {
+		final String s = IOUtils.toString(getClass().getResourceAsStream("input.json"));
+		System.out.println("s = " + s);
+		final ObjectMapper mapper = new ObjectMapper();
+		MDStoreVersion mi = mapper.readValue(s, MDStoreVersion.class);
+
+		assertNotNull(mi);
+
+	}
+
 	@Test
 	public void tesCollection(@TempDir Path testDir) throws Exception {
 		final Provenance provenance = new Provenance("pippo", "puppa", "ns_prefix");
diff --git a/dhp-workflows/dhp-aggregation/src/test/resources/eu/dnetlib/dhp/collection/input.json b/dhp-workflows/dhp-aggregation/src/test/resources/eu/dnetlib/dhp/collection/input.json
new file mode 100644
index 000000000..4ffc33d24
--- /dev/null
+++ b/dhp-workflows/dhp-aggregation/src/test/resources/eu/dnetlib/dhp/collection/input.json
@@ -0,0 +1,9 @@
+{
+  "id": "md-7557225f-77cc-407d-bdf4-d2fe03131464-1611935085410",
+  "mdstore": "md-7557225f-77cc-407d-bdf4-d2fe03131464",
+  "writing": true,
+  "readCount": 0,
+  "lastUpdate": null,
+  "size": 0,
+  "hdfsPath": "/data/dnet.dev/mdstore/md-7557225f-77cc-407d-bdf4-d2fe03131464/md-7557225f-77cc-407d-bdf4-d2fe03131464-1611935085410"
+}
\ No newline at end of file