diff --git a/CHANGES.md b/CHANGES.md
index c441e9e982..26fa18fbdc 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -40,7 +40,14 @@ Release Notes.
 * Fix NPE when OAP nodes synchronize events with each other in cluster mode.
 * Support k8s configmap grouped dynamic configurations.
 * Add desc sort function in H2 and ElasticSearch implementations of IBrowserLogQueryDAO
-* Support configure sampling policy by `configuration module` dynamically and static configuration file `trace-sampling-policy-settings.yml` for service dimension on the backend side. Dynamic configurations `agent-analyzer.default.sampleRate` and `agent-analyzer.default.slowTraceSegmentThreshold` are replaced by `agent-analyzer.default.traceSamplingPolicy`. Static configurations `agent-analyzer.default.sampleRate` and `agent-analyzer.default.slowTraceSegmentThreshold` are replaced by `agent-analyzer.default.traceSamplingPolicySettingsFile`.
+* Support configure sampling policy by `configuration module` dynamically and static configuration
+  file `trace-sampling-policy-settings.yml` for service dimension on the backend side. Dynamic
+  configurations `agent-analyzer.default.sampleRate` and `agent-analyzer.default.slowTraceSegmentThreshold` are replaced
+  by `agent-analyzer.default.traceSamplingPolicy`. Static configurations `agent-analyzer.default.sampleRate`
+  and `agent-analyzer.default.slowTraceSegmentThreshold` are replaced
+  by `agent-analyzer.default.traceSamplingPolicySettingsFile`.
+* Fix dynamic configuration watch implementation current value not null when the config is deleted.
+* Fix `LoggingConfigWatcher` return `watch.value` would not consistent with the real configuration content.
 
 #### UI
 
diff --git a/oap-server/analyzer/agent-analyzer/src/main/java/org/apache/skywalking/oap/server/analyzer/provider/trace/UninstrumentedGatewaysConfig.java b/oap-server/analyzer/agent-analyzer/src/main/java/org/apache/skywalking/oap/server/analyzer/provider/trace/UninstrumentedGatewaysConfig.java
index 3791d52362..7ae50fd765 100644
--- a/oap-server/analyzer/agent-analyzer/src/main/java/org/apache/skywalking/oap/server/analyzer/provider/trace/UninstrumentedGatewaysConfig.java
+++ b/oap-server/analyzer/agent-analyzer/src/main/java/org/apache/skywalking/oap/server/analyzer/provider/trace/UninstrumentedGatewaysConfig.java
@@ -17,6 +17,7 @@
 
 package org.apache.skywalking.oap.server.analyzer.provider.trace;
 
+import com.google.common.base.Strings;
 import java.io.FileNotFoundException;
 import java.io.Reader;
 import java.util.ArrayList;
@@ -35,7 +36,6 @@ import lombok.ToString;
 import lombok.extern.slf4j.Slf4j;
 import org.apache.skywalking.oap.server.analyzer.module.AnalyzerModule;
 import org.apache.skywalking.oap.server.configuration.api.ConfigChangeWatcher;
-import org.apache.skywalking.oap.server.core.Const;
 import org.apache.skywalking.oap.server.library.module.ModuleProvider;
 import org.apache.skywalking.oap.server.library.util.ResourceUtils;
 import org.apache.skywalking.oap.server.library.util.yaml.ClassFilterConstructor;
@@ -51,7 +51,7 @@ public class UninstrumentedGatewaysConfig extends ConfigChangeWatcher {
 
     public UninstrumentedGatewaysConfig(ModuleProvider provider) {
         super(AnalyzerModule.NAME, provider, "uninstrumentedGateways");
-        this.settingsString = new AtomicReference<>(Const.EMPTY_STRING);
+        this.settingsString = new AtomicReference<>(null);
         final GatewayInfos defaultGateways = parseGatewaysFromFile("gateways.yml");
         log.info("Default configured gateways: {}", defaultGateways);
         onGatewaysUpdated(defaultGateways);
@@ -62,13 +62,13 @@ public class UninstrumentedGatewaysConfig extends ConfigChangeWatcher {
             log.debug("Updating using new static config: {}", config);
         }
         this.settingsString.set(config);
-        onGatewaysUpdated(parseGatewaysFromYml(config));
+        onGatewaysUpdated(parseGatewaysFromYml(Strings.nullToEmpty(config)));
     }
 
     @Override
     public void notify(ConfigChangeEvent value) {
         if (EventType.DELETE.equals(value.getEventType())) {
-            activeSetting("");
+            activeSetting(null);
         } else {
             activeSetting(value.getNewValue());
         }
diff --git a/oap-server/server-alarm-plugin/src/main/java/org/apache/skywalking/oap/server/core/alarm/provider/AlarmRulesWatcher.java b/oap-server/server-alarm-plugin/src/main/java/org/apache/skywalking/oap/server/core/alarm/provider/AlarmRulesWatcher.java
index 6b1ea47d30..c9c6cb663f 100644
--- a/oap-server/server-alarm-plugin/src/main/java/org/apache/skywalking/oap/server/core/alarm/provider/AlarmRulesWatcher.java
+++ b/oap-server/server-alarm-plugin/src/main/java/org/apache/skywalking/oap/server/core/alarm/provider/AlarmRulesWatcher.java
@@ -26,7 +26,6 @@ import java.util.Map;
 import lombok.Getter;
 import lombok.extern.slf4j.Slf4j;
 import org.apache.skywalking.oap.server.configuration.api.ConfigChangeWatcher;
-import org.apache.skywalking.oap.server.core.Const;
 import org.apache.skywalking.oap.server.core.alarm.AlarmModule;
 import org.apache.skywalking.oap.server.core.alarm.provider.dingtalk.DingtalkSettings;
 import org.apache.skywalking.oap.server.core.alarm.provider.expression.Expression;
@@ -58,7 +57,7 @@ public class AlarmRulesWatcher extends ConfigChangeWatcher {
         super(AlarmModule.NAME, provider, "alarm-settings");
         this.runningContext = new HashMap<>();
         this.alarmRuleRunningRuleMap = new HashMap<>();
-        this.settingsString = Const.EMPTY_STRING;
+        this.settingsString = null;
         Expression expression = new Expression(new ExpressionContext());
         this.compositeRuleEvaluator = new CompositeRuleEvaluator(expression);
         notify(defaultRules);
@@ -67,7 +66,7 @@ public class AlarmRulesWatcher extends ConfigChangeWatcher {
     @Override
     public void notify(ConfigChangeEvent value) {
         if (value.getEventType().equals(EventType.DELETE)) {
-            settingsString = Const.EMPTY_STRING;
+            settingsString = null;
             notify(new Rules());
         } else {
             settingsString = value.getNewValue();
diff --git a/oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/analysis/ApdexThresholdConfig.java b/oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/analysis/ApdexThresholdConfig.java
index 0ac90f48ca..083eaad6f3 100644
--- a/oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/analysis/ApdexThresholdConfig.java
+++ b/oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/analysis/ApdexThresholdConfig.java
@@ -18,6 +18,7 @@
 
 package org.apache.skywalking.oap.server.core.analysis;
 
+import com.google.common.base.Strings;
 import java.io.FileNotFoundException;
 import java.io.Reader;
 import java.io.StringReader;
@@ -25,7 +26,6 @@ import java.util.Collections;
 import java.util.Map;
 import lombok.extern.slf4j.Slf4j;
 import org.apache.skywalking.oap.server.configuration.api.ConfigChangeWatcher;
-import org.apache.skywalking.oap.server.core.Const;
 import org.apache.skywalking.oap.server.core.CoreModule;
 import org.apache.skywalking.oap.server.core.CoreModuleProvider;
 import org.apache.skywalking.oap.server.library.util.ResourceUtils;
@@ -44,7 +44,7 @@ public class ApdexThresholdConfig extends ConfigChangeWatcher implements Configu
 
     private Map<String, Integer> dictionary = Collections.emptyMap();
 
-    private String rawConfig = Const.EMPTY_STRING;
+    private String rawConfig = null;
 
     public ApdexThresholdConfig(final CoreModuleProvider provider) {
         super(CoreModule.NAME, provider, "apdexThreshold");
@@ -74,7 +74,7 @@ public class ApdexThresholdConfig extends ConfigChangeWatcher implements Configu
     @Override
     public void notify(ConfigChangeEvent value) {
         if (EventType.DELETE.equals(value.getEventType())) {
-            activeSetting("");
+            activeSetting(null);
         } else {
             activeSetting(value.getNewValue());
         }
@@ -90,7 +90,7 @@ public class ApdexThresholdConfig extends ConfigChangeWatcher implements Configu
             log.debug("Updating using new static config: {}", config);
         }
         rawConfig = config;
-        updateConfig(new StringReader(config));
+        updateConfig(new StringReader(Strings.nullToEmpty(config)));
     }
 
     @SuppressWarnings("unchecked")
diff --git a/oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/config/group/EndpointNameGroupingRuleWatcher.java b/oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/config/group/EndpointNameGroupingRuleWatcher.java
index f9cffbf296..d2addf82eb 100644
--- a/oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/config/group/EndpointNameGroupingRuleWatcher.java
+++ b/oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/config/group/EndpointNameGroupingRuleWatcher.java
@@ -47,7 +47,7 @@ public class EndpointNameGroupingRuleWatcher extends ConfigChangeWatcher {
     @Override
     public void notify(final ConfigChangeEvent value) {
         if (value.getEventType().equals(EventType.DELETE)) {
-            ruleSetting = "";
+            ruleSetting = null;
             grouping.setEndpointGroupingRule(new EndpointGroupingRule());
         } else {
             ruleSetting = value.getNewValue();
diff --git a/oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/logging/LoggingConfigWatcher.java b/oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/logging/LoggingConfigWatcher.java
index 6ea59e9295..284c55fd16 100644
--- a/oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/logging/LoggingConfigWatcher.java
+++ b/oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/logging/LoggingConfigWatcher.java
@@ -50,9 +50,10 @@ public class LoggingConfigWatcher extends ConfigChangeWatcher {
     public void notify(final ConfigChangeEvent value) {
         String newValue;
         if (EventType.DELETE.equals(value.getEventType())) {
-            this.content = "";
-            newValue = "";
+            this.content = null;
+            newValue = null;
         } else {
+            this.content = value.getNewValue();
             newValue = value.getNewValue();
         }
         try {
@@ -63,14 +64,6 @@ public class LoggingConfigWatcher extends ConfigChangeWatcher {
             log.error("failed to apply configuration to log4j", t);
             return;
         }
-        StringBuilder builder = new StringBuilder();
-        ctx.getConfiguration().getLoggers().forEach((loggerName, config) -> {
-            builder.append(Strings.isNullOrEmpty(loggerName) ? "Root" : loggerName)
-                   .append(":")
-                   .append(config.getLevel())
-                   .append(",");
-        });
-        this.content = builder.toString();
     }
 
     @Override
diff --git a/oap-server/server-receiver-plugin/configuration-discovery-receiver-plugin/src/main/java/org/apache/skywalking/oap/server/recevier/configuration/discovery/AgentConfigurationsWatcher.java b/oap-server/server-receiver-plugin/configuration-discovery-receiver-plugin/src/main/java/org/apache/skywalking/oap/server/recevier/configuration/discovery/AgentConfigurationsWatcher.java
index a84bd54790..e5ebe394dc 100644
--- a/oap-server/server-receiver-plugin/configuration-discovery-receiver-plugin/src/main/java/org/apache/skywalking/oap/server/recevier/configuration/discovery/AgentConfigurationsWatcher.java
+++ b/oap-server/server-receiver-plugin/configuration-discovery-receiver-plugin/src/main/java/org/apache/skywalking/oap/server/recevier/configuration/discovery/AgentConfigurationsWatcher.java
@@ -20,7 +20,6 @@ package org.apache.skywalking.oap.server.recevier.configuration.discovery;
 
 import org.apache.commons.codec.digest.DigestUtils;
 import org.apache.skywalking.oap.server.configuration.api.ConfigChangeWatcher;
-import org.apache.skywalking.oap.server.core.Const;
 import org.apache.skywalking.oap.server.library.module.ModuleProvider;
 
 import java.io.StringReader;
@@ -36,7 +35,7 @@ public class AgentConfigurationsWatcher extends ConfigChangeWatcher {
 
     public AgentConfigurationsWatcher(ModuleProvider provider) {
         super(ConfigurationDiscoveryModule.NAME, provider, "agentConfigurations");
-        this.settingsString = Const.EMPTY_STRING;
+        this.settingsString = null;
         this.agentConfigurationsTable = new AgentConfigurationsTable();
         this.emptyAgentConfigurations = new AgentConfigurations(
             null, new HashMap<>(), DigestUtils.sha512Hex("EMPTY")
@@ -46,7 +45,7 @@ public class AgentConfigurationsWatcher extends ConfigChangeWatcher {
     @Override
     public void notify(ConfigChangeEvent value) {
         if (value.getEventType().equals(EventType.DELETE)) {
-            settingsString = Const.EMPTY_STRING;
+            settingsString = null;
             this.agentConfigurationsTable = new AgentConfigurationsTable();
         } else {
             settingsString = value.getNewValue();