ESP32 stopped connecting to wi-fi

utopists · October 12, 2023, 10:22am

My project involves connecting to wlfl but it has suddenly stopped connecting. I have tried everything I can think of including running it two different esp32 dev kits run previous project versions that never had a problem connecting ect with no success. Most recently I have run a scanning program to check it can see the network (it can) ; pinned espressif32 to version 5 etc etc!

As a test I am currently using the programme below shown with compile and upload so that you can see the setup I am using.

I am desperate for a lead!

// Demo-Code connect an ESP32 to a WiFi-network using stationmode STA

// stationmode is simply join the WiFi-network as your computer or smartphone does it
// the code has three useful functions one for easy identifiying the code in the flash
// one for non-blocking timing
// a heartbeat-blinker function for indicating the state the code is in

// the code is written with two programming rules:
// 1. put EACH functionality into its OWN function
// 2. give EACH function a SELF-explaining name what the function does
// you should follow these programming rules
#include <WiFi.h>
#include <Wire.h>
#include <SPI.h>
#include <Adafruit_PWMServoDriver.h>

const char *ssid = "yourssid";
const char *password = "yourpassword";

void PrintFileNameDateTime() {
  Serial.println( F("Code running comes from file ") );
  Serial.println( F(__FILE__));
  Serial.print( F("  compiled ") );
  Serial.print(F(__DATE__));
  Serial.print( F(" ") );
  Serial.println(F(__TIME__));
}

boolean TimePeriodIsOver (unsigned long &periodStartTime, unsigned long TimePeriod) {
  unsigned long currentMillis  = millis();
  if ( currentMillis - periodStartTime >= TimePeriod )
  {
    periodStartTime = currentMillis; // set new expireTime
    return true;                // more time than TimePeriod) has elapsed since last time if-condition was true
  }
  else return false;            // not expired
}

unsigned long MyTestTimer = 0;                   // variables MUST be of type unsigned long
const byte    OnBoard_LED = 2;

uint8_t actualWiFiStatus;
uint8_t lastWiFiStatus;

void BlinkHeartBeatLED(int IO_Pin, int BlinkPeriod) {
  static unsigned long MyBlinkTimer;
  pinMode(IO_Pin, OUTPUT);
  if ( TimePeriodIsOver(MyBlinkTimer, BlinkPeriod) ) {
    digitalWrite(IO_Pin, !digitalRead(IO_Pin) );
  }
}

void printWiFiStatus(uint8_t p_WiFiStatus) {
  switch (p_WiFiStatus) {
    
    case WL_IDLE_STATUS:
      Serial.println("WL_IDLE_STATUS temporary status assigned when WiFi.begin() is called");
      break;
      
    case WL_NO_SSID_AVAIL:
      Serial.println("WL_NO_SSID_AVAIL   when no SSID are available");
      break;
      
    case WL_SCAN_COMPLETED:
      Serial.println("WL_SCAN_COMPLETED scan networks is completed");
      break;
      
    case WL_CONNECTED:
      Serial.println("WL_CONNECTED  when connected to a WiFi network");
      break;
      
    case WL_CONNECT_FAILED:
      Serial.println("WL_CONNECT_FAILED when the connection fails for all the attempts");
      break;
      
    case WL_CONNECTION_LOST:
      Serial.println("WL_CONNECTION_LOST  when the connection is lost");
      break;
      
    case WL_DISCONNECTED:
      Serial.println("WL_DISCONNECTED when disconnected from a network");
      break;
  }
  Serial.println();
  Serial.println();
}

void ConnectToWiFi() {
  WiFi.mode(WIFI_STA);
  Serial.println("WiFi.mode(WIFI_STA)");
  int myCount = 0;
  Serial.print("trying to connect to #");
  Serial.print(ssid);
  Serial.println("#");
  WiFi.begin(ssid, password);
  Serial.println("WiFi.begin() done");
  actualWiFiStatus = WiFi.status();
  
  #define maxCount 120
  // Wait for connection
  while (actualWiFiStatus != WL_CONNECTED && myCount < maxCount) {
    actualWiFiStatus = WiFi.status();
    if (lastWiFiStatus != actualWiFiStatus) {
      Serial.println("WiFiStatus changed from");
      printWiFiStatus(lastWiFiStatus);
      Serial.println("to new status");
      printWiFiStatus(actualWiFiStatus);
      lastWiFiStatus = actualWiFiStatus;
    }

    BlinkHeartBeatLED(OnBoard_LED, 50); // blink LED fast during attempt to connect
    yield();
    if ( TimePeriodIsOver(MyTestTimer, 500) ) { // once every 500 miliseconds
      Serial.print(".");                        // print a dot
      myCount++;
      if (myCount > maxCount) { // after maxCount dots restart
        Serial.println();
        Serial.print("not yet connected executing ESP.restart();");
        ESP.restart();
      }
    }
  }
  
  if (WiFi.status() == WL_CONNECTED ) {
    Serial.println("");
    Serial.print("Connected to #");
    Serial.print(ssid);
    Serial.print("# IP address: ");
    Serial.println(WiFi.localIP());
  }
}

void setup() {
  Serial.begin(115200);
  Serial.println( F("Setup-Start") );
  PrintFileNameDateTime();
  ConnectToWiFi();
}

void PrintHelloMsg() {
  Serial.print( F("Hi there I'm the demo-code my IP address is: ") );
  Serial.println(WiFi.localIP());
}

void loop() {
  BlinkHeartBeatLED(OnBoard_LED, 500); // change blinking to a lower frequency indicating beeing connected
  if ( TimePeriodIsOver(MyTestTimer, 1000) ) {
    PrintHelloMsg();
  }
}
/*
  most ESP32 boards have a blue LED connected to GPIO-pin 2
  This blue LED is used to indicate state connecting to WiFi by blinking fast
  state beeing connected to Wifi by blinking with 1 Hz

  If the WiFi-connection is successfully established the serial monitor shows

  08:44:02.915 -> Setup-Start
  08:44:02.915 -> Code running comes from file
  08:44:02.915 -> your-path\ESP32-connect-to-Wifi-Demo-001\ESP32-connect-to-Wifi-Demo-001.ino
  08:44:02.915 ->   compiled date/time of compiling
  08:44:02.971 -> WiFi.mode(WIFI_STA)
  08:44:02.971 -> trying to connect to #Your SSID#
  08:44:03.362 -> ....
  08:44:04.215 -> Connected to #Your SSID# IP address: given IP-adress NNN.NNN.NNN.NNN
  08:44:04.865 -> Hi there I'm the demo-code my IP address is: NNN.NNN.NNN.NNN

  if there is something wrong with your WiFi, SSID or password
  you will see this in the serial monitor
  08:32:36.598 -> Setup-Start
  08:32:36.598 -> Code running comes from file
  08:32:36.598 -> F:\MyPortable-PRgs\arduino-1.8.16-newb\portable\sketchbook\ESP32-connect-to-Wifi-Demo-001\ESP32-connect-to-Wifi-Demo-001.ino
  08:32:36.598 ->   compiled Dec  1 2021 08:32:18
  08:32:36.684 -> WiFi.mode(WIFI_STA)
  08:32:36.684 -> trying to connect to #your SSID#
  08:32:37.036 -> ...............................
  08:32:52.035 -> not yet connected executing ESP.restart();ets Jun  8 2016 00:22:57
  08:32:52.035 ->
  08:32:52.035 -> rst:0xc (SW_CPU_RESET),boot:0x13 (SPI_FAST_FLASH_BOOT)
  08:32:52.035 -> configsip: 0, SPIWP:0xee
  08:32:52.035 -> clk_drv:0x00,q_drv:0x00,d_drv:0x00,cs0_drv:0x00,hd_drv:0x00,wp_drv:0x00
  08:32:52.073 -> mode:DIO, clock div:1
  08:32:52.073 -> load:0x3fff0018,len:4
  08:32:52.073 -> load:0x3fff001c,len:1216
  08:32:52.073 -> ho 0 tail 12 room 4
  08:32:52.073 -> load:0x40078000,len:9720
  08:32:52.073 -> ho 0 tail 12 room 4
  08:32:52.073 -> load:0x40080400,len:6352
  08:32:52.073 -> entry 0x400806b8
  08:32:52.309 -> Setup-Start
  08:32:52.309 -> Code running comes from file
  08:32:52.309 -> F:\MyPortable-PRgs\arduino-1.8.16-newb\portable\sketchbook\ESP32-connect-to-Wifi-Demo-001\ESP32-connect-to-Wifi-Demo-001.ino
  08:32:52.309 ->   compiled Dec  1 2021 08:32:18
  08:32:52.405 -> WiFi.mode(WIFI_STA)
  08:32:52.405 -> trying to connect to #Your SSID#
  08:32:52.758 -> ...............................
  08:33:07.788 -> not yet connected executing ESP.restart();ets Jun  8 2016 00:22:57

*/

It compiles and uploads fine…

 *  Executing task in folder ESPSERVOs: platformio run --target upload --upload-port /dev/ttyACM0 
Processing esp32dev (platform: espressif32 @ ^5.0.0; board: esp32dev; framework: arduino)
-----------------------------------------------------------------------------------------------------------------
Verbose mode can be enabled via `-v, --verbose` option
CONFIGURATION: https://docs.platformio.org/page/boards/espressif32/esp32dev.html
PLATFORM: Espressif 32 (5.4.0) > Espressif ESP32 Dev Module
HARDWARE: ESP32 240MHz, 320KB RAM, 4MB Flash
DEBUG: Current (cmsis-dap) External (cmsis-dap, esp-bridge, esp-prog, iot-bus-jtag, jlink, minimodule, olimex-arm-usb-ocd, olimex-arm-usb-ocd-h, olimex-arm-usb-tiny-h, olimex-jtag-tiny, tumpa)
PACKAGES: 
 - framework-arduinoespressif32 @ 3.20006.221224 (2.0.6) 
 - tool-esptoolpy @ 1.40400.0 (4.4.0) 
 - tool-mkfatfs @ 2.0.1 
 - tool-mklittlefs @ 1.203.210628 (2.3) 
 - tool-mkspiffs @ 2.230.0 (2.30) 
 - toolchain-xtensa-esp32 @ 8.4.0+2021r2-patch5
LDF: Library Dependency Finder -> https://bit.ly/configure-pio-ldf
LDF Modes: Finder ~ chain, Compatibility ~ soft
Found 37 compatible libraries
Scanning dependencies...
Dependency Graph
|-- Adafruit PWM Servo Driver Library @ 3.0.1
|-- Adafruit BusIO @ 1.14.4
|-- SPI @ 2.0.0
|-- WiFi @ 2.0.0
|-- Wire @ 2.0.0
Building in release mode
Compiling .pio/build/esp32dev/src/wifistatus.cpp.o
Building .pio/build/esp32dev/bootloader.bin
esptool.py v4.4
Creating esp32 image...
Merged 1 ELF section
Successfully created esp32 image.........

ECT ECT.....

It creates the following output to indicate that it has not been able to connect…

Code running comes from file 
src/wifistatus.cpp
  compiled Oct 12 2023 10:13:42
WiFi.mode(WIFI_STA)
trying to connect to #BT-THAJX6#
WiFi.begin() done
WiFiStatus changed from
WL_IDLE_STATUS temporary status assigned when WiFi.begin() is calledto new status
WL_DISCONNECTED when disconnected from a network

........................................................................................................................Hi there I'm the demo-code my IP address is: 0.0.0.0
Hi there I'm the demo-code my IP address is: 0.0.0.0 ....

and on and on!

utopists · October 16, 2023, 5:19pm

I have since run the code on two different ESP32s and on a completely different router and wifi service all to no avail.*

maxgerhardt · October 17, 2023, 8:34am

Does it fail when using the Arduino IDE too? If yes, the problem is not PlatformIO specific and you could get help at https://github.com/espressif/arduino-esp32/issues.

Something I can generally recommend is to just trigger a flash erase with esptool.py and flash anew. https://randomnerdtutorials.com/esp32-erase-flash-memory/

jaca2300 · October 18, 2023, 4:37am

Did you enter your SSID and Password in:

And I Think every project have to start with
#include <Arduino.h>

utopists · October 19, 2023, 3:42am

Yes appropriate wifi credentials were added in every case. Well spotted indeed! I slipped when selecting to copy the code and missed out the top line which was #include

Thanks for your attention.

utopists · October 19, 2023, 2:07pm

Thank you. I’ve come to a similar conclusion i.e. reflash the esp32 so as to eliminate the possibilty that it is due to some sort of corruption -I will report back in due course.

utopists · October 22, 2023, 7:34pm

Simple (as it turned out) solution proved to be erasing the flash memory:

python -m esptool --chip esp32 erase_flash

The issue remains as to how you identify this by receiving error signals and from where? but at least its solved.

ronalddmas · October 24, 2025, 12:01pm

I unplugged the ESP32S3 while it was connecting to WiFI (to move to a new location). After this, it could not connect to WiFi any longer. Reflashing the firmware did not work - reflashing the ‘sketch data’ however solved the issue. Thus it appears that some part of the flash got corrupted other than the code.

What I learnt: Hold the reset button while unplugging power to avoid flash corruption….

sivar2311 · October 24, 2025, 12:15pm

The ESP32 stores the WiFi credentials after a successful connect in the FLASH memory.
This allows you (next time) to call WiFi.begin() (without credentials) to connect to the accespoint.

It looks like you reset the ESP32 just in that moment when it was writing the credentials onto the FLASH memory.

ronalddmas · October 25, 2025, 6:29am

Danke, Silvan!

OK - I unplugged when ESP32 was performaning a WiFi scan. Furthermore, I always WiFi.begin() with full credentials. To me it seems that the WiFi code writes more to flash than credentials.

Do you know if there is a way to have WiFi reset its flash content?

sivar2311 · October 25, 2025, 7:54am

Scanning is a different thing as connecting (as you wrote before).
Afaik while scanning no credentials are written to the flash.

A call to disconnect() with the parameter eraseap set to true: WiFi.disconnect(true); - See arduino-esp32/libraries/WiFi/src/STA.cpp at master · espressif/arduino-esp32 · GitHub