diff --git a/src/main/java/com/exactpro/th2/FixHandler.java b/src/main/java/com/exactpro/th2/FixHandler.java
index 5a547d3..29bbdcf 100644
--- a/src/main/java/com/exactpro/th2/FixHandler.java
+++ b/src/main/java/com/exactpro/th2/FixHandler.java
@@ -754,8 +754,6 @@ public void onOutgoingUpdateTag(@NotNull ByteBuf message, @NotNull Map<String, S
 
         if (beginString == null) {
             beginString = firstField(message).insertPrevious(BEGIN_STRING_TAG, settings.getBeginString());
-        } else if (!settings.getBeginString().equals(beginString.getValue())) {
-            beginString.setValue(settings.getBeginString());
         }
 
         FixField bodyLength = findField(message, BODY_LENGTH_TAG, US_ASCII, beginString);
@@ -777,61 +775,68 @@ public void onOutgoingUpdateTag(@NotNull ByteBuf message, @NotNull Map<String, S
         FixField checksum = findLastField(message, CHECKSUM_TAG);
 
         if (checksum == null) { // Length is updated at the of the current method
-            lastField(message).insertNext(CHECKSUM_TAG, STUBBING_VALUE); //stubbing until finish checking message
+            checksum = lastField(message).insertNext(CHECKSUM_TAG, STUBBING_VALUE); //stubbing until finish checking message
         }
 
         FixField msgSeqNum = findField(message, MSG_SEQ_NUM_TAG, US_ASCII, bodyLength);
 
-        String msgSeqNumValue = Integer.toString(this.msgSeqNum.incrementAndGet());
         if (msgSeqNum == null) {
+            int msgSeqNumValue = this.msgSeqNum.incrementAndGet();
+
             if (msgType != null) {
-                msgSeqNum = msgType.insertNext(MSG_SEQ_NUM_TAG, msgSeqNumValue);
+                msgSeqNum = msgType.insertNext(MSG_SEQ_NUM_TAG, Integer.toString(msgSeqNumValue));
             } else {
-                msgSeqNum = bodyLength.insertNext(MSG_SEQ_NUM_TAG, msgSeqNumValue);
+                msgSeqNum = bodyLength.insertNext(MSG_SEQ_NUM_TAG, Integer.toString(msgSeqNumValue));
             }
-        } else {
-            msgSeqNum.setValue(msgSeqNumValue);
         }
 
         FixField senderCompID = findField(message, SENDER_COMP_ID_TAG, US_ASCII, bodyLength);
 
         if (senderCompID == null) {
             senderCompID = msgSeqNum.insertNext(SENDER_COMP_ID_TAG, settings.getSenderCompID());
-        } else if (!settings.getSenderCompID().equals(senderCompID.getValue())) {
-            senderCompID.setValue(settings.getSenderCompID());
+        } else {
+            String value = senderCompID.getValue();
+
+            if (value == null || value.isEmpty() || value.equals("null")) {
+                senderCompID.setValue(settings.getSenderCompID());
+            }
         }
 
         FixField targetCompID = findField(message, TARGET_COMP_ID_TAG, US_ASCII, bodyLength);
 
         if (targetCompID == null) {
             targetCompID = senderCompID.insertNext(TARGET_COMP_ID_TAG, settings.getTargetCompID());
-        } else if (!settings.getTargetCompID().equals(targetCompID.getValue())) {
-            targetCompID.setValue(settings.getTargetCompID());
-        }
-
-        FixField senderSubID = findField(message, SENDER_SUB_ID_TAG, US_ASCII, bodyLength);
-        if (senderSubID == null) {
-            if (settings.getSenderSubID() != null) {
-                targetCompID.insertNext(SENDER_SUB_ID_TAG, settings.getSenderSubID());
-            }
         } else {
-            if (settings.getSenderSubID() == null) {
-                senderSubID.clear();
-            } else if (!settings.getSenderSubID().equals(senderSubID.getValue())) {
-                senderSubID.setValue(settings.getSenderSubID());
+            String value = targetCompID.getValue();
+
+            if (value == null || value.isEmpty() || value.equals("null")) {
+                targetCompID.setValue(settings.getTargetCompID());
             }
         }
 
-        LOGGER.info("Body length field: {}", new String(bodyLength.getBytes()));
+        if (settings.getSenderSubID() != null) {
+            FixField senderSubID = findField(message, SENDER_SUB_ID_TAG, US_ASCII, bodyLength);
+
+            if (senderSubID == null) {
+                senderSubID = targetCompID.insertNext(SENDER_SUB_ID_TAG, settings.getSenderSubID());
+            } else {
+                String value = senderSubID.getValue();
+
+                if (value == null || value.isEmpty() || value.equals("null")) {
+                    senderSubID.setValue(settings.getSenderSubID());
+                }
+            }
+        }
         FixField sendingTime = findField(message, SENDING_TIME_TAG, US_ASCII, bodyLength);
-        LOGGER.info("Message before adding sending time: {}", message.toString(StandardCharsets.UTF_8));
+
         if (sendingTime == null) {
-            LOGGER.info("Sending time tag value 1: {}", new String(targetCompID.getBytes()));
             targetCompID.insertNext(SENDING_TIME_TAG, getTime());
         } else {
-            LOGGER.info("Sending time tag value 2: {}", new String(sendingTime.getBytes()));
-            sendingTime.setValue(getTime());
-            LOGGER.info("Sending time tag value 3: {}", new String(sendingTime.getBytes()));
+            String value = sendingTime.getValue();
+
+            if (value == null || value.isEmpty() || value.equals("null")) {
+                sendingTime.setValue(getTime());
+            }
         }
 
         updateLength(message);
diff --git a/src/main/kotlin/com/exactpro/th2/conn/dirty/fix/FixByteBufUtil.kt b/src/main/kotlin/com/exactpro/th2/conn/dirty/fix/FixByteBufUtil.kt
index fc80dc7..2971f2c 100644
--- a/src/main/kotlin/com/exactpro/th2/conn/dirty/fix/FixByteBufUtil.kt
+++ b/src/main/kotlin/com/exactpro/th2/conn/dirty/fix/FixByteBufUtil.kt
@@ -44,7 +44,6 @@ fun ByteBuf.firstField(charset: Charset = UTF_8): FixField? = FixField.atOffset(
 @JvmOverloads
 fun ByteBuf.lastField(charset: Charset = UTF_8): FixField? = FixField.atOffset(this, writerIndex() - 1, charset)
 
-val K_LOGGER = KotlinLogging.logger {  }
 @JvmOverloads
 inline fun ByteBuf.forEachField(
     charset: Charset = UTF_8,
@@ -53,12 +52,9 @@ inline fun ByteBuf.forEachField(
 ) {
     var field = start
 
-    field?.bytes?.let { K_LOGGER.info { "Processing field: ${String(it)}" } }
-
     while (field != null) {
         action(field)
         field = field.next()
-        field?.bytes?.let { K_LOGGER.info { "Processing field: ${String(it)}" } }
     }
 }