diff --git a/server/bundles/io.cloudbeaver.server/src/io/cloudbeaver/service/sql/WebSQLCellValueReceiver.java b/server/bundles/io.cloudbeaver.server/src/io/cloudbeaver/service/sql/WebSQLCellValueReceiver.java
index 60f151df2a..65fa368a5d 100644
--- a/server/bundles/io.cloudbeaver.server/src/io/cloudbeaver/service/sql/WebSQLCellValueReceiver.java
+++ b/server/bundles/io.cloudbeaver.server/src/io/cloudbeaver/service/sql/WebSQLCellValueReceiver.java
@@ -43,7 +43,7 @@ public class WebSQLCellValueReceiver implements DBDDataReceiver {
     @Override
     public void fetchStart(@NotNull DBCSession session, @NotNull DBCResultSet resultSet, long offset, long maxRows) throws DBCException {
         DBCResultSetMetaData meta = resultSet.getMeta();
-        List<DBCAttributeMetaData> attributes = meta.getAttributes();
+        List<? extends DBCAttributeMetaData> attributes = meta.getAttributes();
         DBCAttributeMetaData attrMeta = attributes.get(rowIndex);
         binding = new DBDAttributeBindingMeta(dataContainer, resultSet.getSession(), attrMeta);
     }
diff --git a/server/bundles/io.cloudbeaver.server/src/io/cloudbeaver/service/sql/WebSQLContextInfo.java b/server/bundles/io.cloudbeaver.server/src/io/cloudbeaver/service/sql/WebSQLContextInfo.java
index 4856ed809b..13862f2125 100644
--- a/server/bundles/io.cloudbeaver.server/src/io/cloudbeaver/service/sql/WebSQLContextInfo.java
+++ b/server/bundles/io.cloudbeaver.server/src/io/cloudbeaver/service/sql/WebSQLContextInfo.java
@@ -51,7 +51,7 @@ public class WebSQLContextInfo implements WebSessionProvider {
 
     private static final Log log = Log.getLog(WebSQLContextInfo.class);
 
-    private final WebSQLProcessor processor;
+    private final transient WebSQLProcessor processor;
     private final String id;
     private final String projectId;
     private final Map<String, WebSQLResultsInfo> resultInfoMap = new HashMap<>();
diff --git a/server/bundles/io.cloudbeaver.server/src/io/cloudbeaver/service/sql/WebSQLProcessor.java b/server/bundles/io.cloudbeaver.server/src/io/cloudbeaver/service/sql/WebSQLProcessor.java
index a6b01c916d..0e66210d10 100644
--- a/server/bundles/io.cloudbeaver.server/src/io/cloudbeaver/service/sql/WebSQLProcessor.java
+++ b/server/bundles/io.cloudbeaver.server/src/io/cloudbeaver/service/sql/WebSQLProcessor.java
@@ -1062,7 +1062,7 @@ public class WebSQLProcessor implements WebSessionProvider {
             DBDAttributeBinding[] resultsAttributes = results.getAttributes();
 
             DBCResultSetMetaData rsMeta = resultSet.getMeta();
-            List<DBCAttributeMetaData> keyAttributes = rsMeta.getAttributes();
+            List<? extends DBCAttributeMetaData> keyAttributes = rsMeta.getAttributes();
             for (int i = 0; i < keyAttributes.size(); i++) {
                 DBCAttributeMetaData keyAttribute = keyAttributes.get(i);
                 DBDValueHandler valueHandler = DBUtils.findValueHandler(session, keyAttribute);
diff --git a/server/bundles/io.cloudbeaver.server/src/io/cloudbeaver/service/sql/WebSQLQueryDataContainer.java b/server/bundles/io.cloudbeaver.server/src/io/cloudbeaver/service/sql/WebSQLQueryDataContainer.java
index 0c5d2c0d2f..b8ab7b7af7 100644
--- a/server/bundles/io.cloudbeaver.server/src/io/cloudbeaver/service/sql/WebSQLQueryDataContainer.java
+++ b/server/bundles/io.cloudbeaver.server/src/io/cloudbeaver/service/sql/WebSQLQueryDataContainer.java
@@ -94,7 +94,16 @@ public class WebSQLQueryDataContainer implements DBSDataContainer, DBPContextPro
 
     @NotNull
     @Override
-    public DBCStatistics readData(@NotNull DBCExecutionSource source, @NotNull DBCSession session, @NotNull DBDDataReceiver dataReceiver, @Nullable DBDDataFilter dataFilter, long firstRow, long maxRows, long flags, int fetchSize) throws DBCException {
+    public DBCStatistics readData(
+        @Nullable DBCExecutionSource source,
+        @NotNull DBCSession session,
+        @NotNull DBDDataReceiver dataReceiver,
+        @Nullable DBDDataFilter dataFilter,
+        long firstRow,
+        long maxRows,
+        long flags,
+        int fetchSize
+    ) throws DBCException {
         return queryDataContainer.readData(source, session, dataReceiver, dataFilter, firstRow, maxRows, flags, fetchSize);
     }
 
diff --git a/server/bundles/io.cloudbeaver.server/src/io/cloudbeaver/service/sql/WebSQLQueryDataReceiver.java b/server/bundles/io.cloudbeaver.server/src/io/cloudbeaver/service/sql/WebSQLQueryDataReceiver.java
index de21430566..957b322f7f 100644
--- a/server/bundles/io.cloudbeaver.server/src/io/cloudbeaver/service/sql/WebSQLQueryDataReceiver.java
+++ b/server/bundles/io.cloudbeaver.server/src/io/cloudbeaver/service/sql/WebSQLQueryDataReceiver.java
@@ -65,7 +65,7 @@ class WebSQLQueryDataReceiver implements DBDDataReceiver {
     @Override
     public void fetchStart(@NotNull DBCSession session, @NotNull DBCResultSet dbResult, long offset, long maxRows) throws DBCException {
         DBCResultSetMetaData meta = dbResult.getMeta();
-        List<DBCAttributeMetaData> attributes = meta.getAttributes();
+        List<? extends DBCAttributeMetaData> attributes = meta.getAttributes();
         bindings = new DBDAttributeBindingMeta[attributes.size()];
         for (int i = 0; i < attributes.size(); i++) {
             DBCAttributeMetaData attrMeta = attributes.get(i);
diff --git a/server/bundles/io.cloudbeaver.server/src/io/cloudbeaver/service/sql/WebSQLQueryResultSet.java b/server/bundles/io.cloudbeaver.server/src/io/cloudbeaver/service/sql/WebSQLQueryResultSet.java
index 73adabbb4a..d7dba7e9cd 100644
--- a/server/bundles/io.cloudbeaver.server/src/io/cloudbeaver/service/sql/WebSQLQueryResultSet.java
+++ b/server/bundles/io.cloudbeaver.server/src/io/cloudbeaver/service/sql/WebSQLQueryResultSet.java
@@ -19,11 +19,9 @@ package io.cloudbeaver.service.sql;
 import org.jkiss.dbeaver.Log;
 import org.jkiss.dbeaver.model.data.DBDAttributeBinding;
 import org.jkiss.dbeaver.model.meta.Property;
-import org.jkiss.utils.Pair;
 
-import java.util.Arrays;
+import java.util.Collections;
 import java.util.List;
-import java.util.Map;
 
 /**
  * Web SQL query resultset.
@@ -33,7 +31,7 @@ public class WebSQLQueryResultSet {
     private static final Log log = Log.getLog(WebSQLQueryResultSet.class);
 
     private WebSQLQueryResultColumn[] columns;
-    private List<WebSQLQueryResultSetRow> rows;
+    private List<WebSQLQueryResultSetRow> rows = Collections.emptyList();
     private boolean hasMoreData;
     private WebSQLResultsInfo resultsInfo;
     private boolean singleEntity = true;
diff --git a/server/bundles/io.cloudbeaver.server/src/io/cloudbeaver/service/sql/impl/WebServiceSQL.java b/server/bundles/io.cloudbeaver.server/src/io/cloudbeaver/service/sql/impl/WebServiceSQL.java
index e07d0e24cd..d6760fb16c 100644
--- a/server/bundles/io.cloudbeaver.server/src/io/cloudbeaver/service/sql/impl/WebServiceSQL.java
+++ b/server/bundles/io.cloudbeaver.server/src/io/cloudbeaver/service/sql/impl/WebServiceSQL.java
@@ -33,7 +33,9 @@ import org.jkiss.dbeaver.model.DBPDataSource;
 import org.jkiss.dbeaver.model.DBPDataSourceContainer;
 import org.jkiss.dbeaver.model.DBUtils;
 import org.jkiss.dbeaver.model.data.DBDAttributeBinding;
-import org.jkiss.dbeaver.model.exec.*;
+import org.jkiss.dbeaver.model.exec.DBCException;
+import org.jkiss.dbeaver.model.exec.DBCLogicalOperator;
+import org.jkiss.dbeaver.model.exec.DBExecUtils;
 import org.jkiss.dbeaver.model.impl.sql.BasicSQLDialect;
 import org.jkiss.dbeaver.model.navigator.DBNNode;
 import org.jkiss.dbeaver.model.runtime.DBRProgressMonitor;