ESP32 OTA update keeps crashing on start


I'm trying to OTA update the ESP32 by letting it make a get request to a file on Azure blob storage.

For some unknown reason it won't let me use the WifiClient.connect() function, since it always returns a 0. So now I'm using the HTTPClient library to make a get request to a blob storage on Azure. I got it to make the request and now I'm trying to stream it into:


But whenever I get to that part, it crashes and gives met the following message:

Guru Meditation Error: Core  1 panic'ed (InstrFetchProhibited). Exception was unhandled.
Core 1 register dump:
PC      : 0x00000000  PS      : 0x00060630  A0      : 0x800d1a18  A1      : 0x3ffb1f30  
A2      : 0x00000000  A3      : 0x3ffb1f64  A4      : 0x3ffc11b8  A5      : 0x00000000  
A6      : 0x3ffbd484  A7      : 0x00000000  A8      : 0x800d3304  A9      : 0x3ffb1f10  
A10     : 0x3ffb1f64  A11     : 0x3f40124c  A12     : 0x00000001  A13     : 0x3ffbd44c  
A14     : 0x00000000  A15     : 0x3ffc1678  SAR     : 0x0000000a  EXCCAUSE: 0x00000014  
EXCVADDR: 0x00000000  LBEG    : 0x400014fd  LEND    : 0x4000150d  LCOUNT  : 0xffffffff  

Backtrace: 0x00000000:0x3ffb1f30 0x400d1a15:0x3ffb1f50 0x400d63bb:0x3ffb1fb0 0x40088b9d:0x3ffb1fd0

Here is the code:

  int httpCode = http.GET();
  if (httpCode > 0) {
    if (httpCode == HTTP_CODE_OK) {
      WiFiClient * stream = http.getStreamPtr();

  unsigned long timeout = millis();
while (stream->available() == 0) {
  if (millis() - timeout > 5000) {
    Serial.println("Client Timeout !");

int contentLength = http.getSize();

  if (Update.begin(contentLength)) {
    Serial.println("Begin OTA. This may take 2 - 5 mins to complete. Things might be quite for a while.. Patience!");
    // No activity would appear on the Serial monitor
    // So be patient. This may take 2 - 5mins to complete
    size_t written = Update.writeStream((WiFiClient &)stream);

    if (written == contentLength) {
      Serial.println("Written : " + String(written) + " successfully");
    } else {
      Serial.println("Written only : " + String(written) + "/" + String(contentLength) + ". Retry?" );
      // retry??
      // execOTA();

    if (Update.end()) {
      Serial.println("OTA done!");
      if (Update.isFinished()) {
        Serial.println("Update successfully completed. Rebooting.");
      } else {
        Serial.println("Update not finished? Something went wrong!");
    } else {
      Serial.println("Error Occurred. Error #: " + String(Update.getError()));

  else {
    Serial.println("Not enough space");

How can I make this code work so that the device will GET the file from the Azure blob storage and update itself?


1 Answer


You have to find out why it is crashing. The Backtrace does not help you without a tool.

Please install this tool in your Arduino IDE:

And put your error inside it to get the calling stack and see where it is crashing. Probably it has nothing to do with the Update but only with the httpclient.

You are calling a https page, do you use the secureClient and do you use a SSL certificate? Without it, you will not be able to communicate over a secure connection.

And finally: VERBOSE
Compile with verbose mode active. It is really important to get every message when something does not work. And for the https, every info is very important to find out why it doesn't work like expected.

answered on Stack Overflow Nov 5, 2019 by Adriano

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