diff --git a/_how-to-develop.md b/_how-to-develop.md
index 4763683..140bd98 100644
--- a/_how-to-develop.md
+++ b/_how-to-develop.md
@@ -1,28 +1,32 @@
-# how to develop web ui
+# how to develop
 
-## copy files except config.html to static/
+## arduino code
 
-```
-cd embed
-rsync -v --exclude=config.html ./* static
-```
+1. git clone
+2. open directory in VSCode
+3. Fix includePath
 
-## run python http.server or some simple web server on embed
+### include path
+
+Edit `.vscode/c_cpp_properties.json` file.
 
 ```
-cd embed
-python -m http.server
+"includePath": [
+    "${workspaceFolder}/**",
+    "/Users/username/.platformio/packages/**"  <-- Add this. path vary on your OS.
+],
 ```
 
-## Access web via web browser
+## Web UI code
 
-Use firefox or chrome newer version.
+1. git clone
+2. edit `src/global.cpp` `DEBUG_BUILD = true`. by change this, envboy returns CORS header.
+3. Upload to board
+4. exec `python -m http.server` In `embed` directory
+5. access `localhost:8000` using web browser
 
-# after development
+### NOTE
 
-Dont forget to write back all files in static/ to embed.
+1. you cant use external JS libraries. because host has no internet access while in setup mode.
 
-```
-cd embed/static
-cp -v ./* ../
-```
\ No newline at end of file
+NOTE: modernize JS/Web development is a task in near future.
\ No newline at end of file
diff --git a/include/config/config.h b/include/config/config.h
index 9583208..ae964c0 100644
--- a/include/config/config.h
+++ b/include/config/config.h
@@ -7,6 +7,8 @@
 #include "config_values.h"
 #include "ConfigClass.h"
 
+extern const String CFG_VERSION_INVALID;
+
 enum struct CFG_VALIDATE_RESULT {
   // 存在していて、バージョンも一致している
   VALID,
diff --git a/src/config/config.cpp b/src/config/config.cpp
index 8592823..5032f0e 100644
--- a/src/config/config.cpp
+++ b/src/config/config.cpp
@@ -12,6 +12,8 @@
 #include "config_names.h"
 
 const unsigned int CONF_JSON_SIZE = 4000;
+extern const String CFG_VERSION_INVALID = "INVALID";
+
 
 DynamicJsonDocument _create_config_json(bool save, const std::vector<String> &keyArray) {
 
@@ -119,12 +121,12 @@ String read_config_setting_id(File f) {
   DeserializationError error = deserializeJson(doc, f);
 
   if (error) {
-    return "INVALID";
+    return CFG_VERSION_INVALID;
   }
 
   JsonVariant value = doc[ConfigNames::SETTING_ID];
   if (value.isNull()) {
-    return "INVALID"; // JSON not contains SETTING_ID
+    return CFG_VERSION_INVALID; // JSON not contains SETTING_ID
   }
 
   return value.as<String>();
diff --git a/src/config/config_file.cpp b/src/config/config_file.cpp
index 75735f9..90b159f 100644
--- a/src/config/config_file.cpp
+++ b/src/config/config_file.cpp
@@ -71,7 +71,10 @@ CFG_VALIDATE_RESULT has_valid_config_file() {
     settingId = read_config_setting_id(f);
     f.close();
 
-    if (String(SETTING_ID).equals(settingId)) {
+    if (settingId.equals(CFG_VERSION_INVALID)) {
+      cfglog("SETTING_ID not found. INVALID config.");
+      return CFG_VALIDATE_RESULT::ERROR;
+    } else if (String(SETTING_ID).equals(settingId)) {
       cfglog("SETTING_ID verified. " + settingId);
       return CFG_VALIDATE_RESULT::VALID;
     } else {
@@ -80,7 +83,7 @@ CFG_VALIDATE_RESULT has_valid_config_file() {
     }
   }
 
-  cfglog("Unknown state. Assuming config not found");
+  cfglog("Unknown state. Assuming config not found. " + settingId);
   return CFG_VALIDATE_RESULT::ERROR;
 }
 
@@ -102,6 +105,7 @@ bool has_configured_file() {
   return true;
 }
 
+/** ファイルシステムのマウント */
 void config_setup() {
 
   if (!LittleFS.begin()) {
diff --git a/src/i2c_scan.cpp b/src/i2c_scan.cpp
index 466fc5f..500d76d 100644
--- a/src/i2c_scan.cpp
+++ b/src/i2c_scan.cpp
@@ -5,54 +5,43 @@
 
 String get_device_name_by_address(byte address) {
   // ("0x39=TSL2561/0x3c=LCD/0x5c=AM2320/0x5d=LPS22HB/0x76=BME280"));
+  if (address == 0x23) return "BH1750 Lux sensor";
   if (address == 0x39) return "TSL2561 Lux sensor";
   if (address == 0x3c) return "SSD1306/SH1106 OLED display";
   if (address == 0x5c) return "AM2320 Temperature and Humidity sensor";
   if (address == 0x5d) return "LPS22HB High precision air pressure sensor";
-  if (address == 0x76) return "BME280 Temperature and Humidity and air pressure sensor";
-
+  if (address == 0x76)
+    return "BME280 Temperature and Humidity and air pressure sensor";
   return "unknown device";
 }
 
-void i2c_scan()
-{
-
+void i2c_scan() {
   unsigned long start = millis();
 
   byte error, address;
   int nDevices = 0;
-  for(address = 1; address < 127; address++ )
-  {
-
+  for (address = 1; address < 127; address++) {
     Wire.beginTransmission(address);
     error = Wire.endTransmission();
- 
-    if (error == 0)
-    {
+
+    if (error == 0) {
       String msg = "Found at 0x";
-      if (address<16)
-        msg += "0";
-      msg += String(address,HEX);
+      if (address < 16) msg += "0";
+      msg += String(address, HEX);
       msg += " " + String(address);
       i2clog(msg + " " + get_device_name_by_address(address));
       nDevices++;
-    }
-    else if (error==4)
-    {
+    } else if (error == 4) {
       String msg = "Unknown error at address 0x";
-      if (address<16)
-        msg += "0";
-      msg += String(address,HEX);
+      if (address < 16) msg += "0";
+      msg += String(address, HEX);
       i2clog(msg);
     }
   }
 
   if (nDevices == 0) {
     i2clog(F("No I2C devices found"));
-  } else {
-    i2clog(F("0x39=TSL2561/0x3c=LCD/0x5c=AM2320/0x5d=LPS22HB/0x76=BME280"));
   }
 
   i2clog("I2C scan done. time = " + String(millis() - start) + " ms");
-
 }
diff --git a/src/main.cpp b/src/main.cpp
index fd77b68..ba9bcb5 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -41,7 +41,10 @@ void setup()
   if (validateResult == CFG_VALIDATE_RESULT::VALID) {
     mainlog(F("Config file is valid."));
   } else if (validateResult == CFG_VALIDATE_RESULT::NEED_UPGRADE) {
-    mainlog(F("Config file needs upgrade."));
+    sectionlog(F("Config file needs upgrade. upgrading..."));
+    read_config();
+    save_config();  // upgrade means json + default, so only saving is needed.
+    sectionlog(F("Config file upgrade done!"));
   } else {
     mainlog(F("Config file validation error. dropping to setup mode."));
     isNormal = false;
diff --git a/src/main_normal.cpp b/src/main_normal.cpp
index aaa7dfa..8c62400 100644
--- a/src/main_normal.cpp
+++ b/src/main_normal.cpp
@@ -143,7 +143,7 @@ void setup_normal() {
   sectionlog(F("Start watchdog"));
   setup_watchdog();
 
-  // setupモードに入りやすくするための処理
+  // setupモードに入りやすくするための処理(deprecated)
   if (config->get(ConfigNames::DISPLAY_RECONFIG) == ConfigValues::DISPLAY_RECONFIG_ON) {
     sectionlog(F("Reset to reconfig start."));
     remove_configure_flag_file();
diff --git a/src/sensors/bh1750.cpp b/src/sensors/bh1750.cpp
index 00fbe34..4f8349d 100644
--- a/src/sensors/bh1750.cpp
+++ b/src/sensors/bh1750.cpp
@@ -24,16 +24,16 @@ bool bh_setup(void) {
   byte error = Wire.endTransmission();
 
   if (!(error == 0)) {
-    amlog(F("BH1750 disabled. "));
+    bhlog(F("BH1750 disabled. "));
     return false;
   }
 
   if (!bh1750.begin(BH1750::CONTINUOUS_HIGH_RES_MODE)) {
-    amlog(F("BH1750 disabled: Device found but initialize error. "));
+    bhlog(F("BH1750 disabled: Device found but initialize error. "));
     return false;
   }
 
-  amlog(F("BH1750 Enabled"));
+  bhlog(F("BH1750 Enabled"));
   use_bh1750 = true;
   return true;
 }