ESP32 OTA Update via HTTP Fails Mid-Transfer

In this tutorial, you'll learn about ESP32 OTA Update via HTTP Fails Mid. We cover key concepts, practical examples, and best practices.

The Problem

ESP32 OTA firmware update from HTTP server fails partway through the transfer.

Quick Fix

Wrong

Update.begin(totalSize);
Update.writeStream(http.getStream());

Update fails at random percentages. ESP32 bricks.

Right

if (Update.begin(http.getSize())) {
  size_t written = Update.writeStream(http.getStream());
  if (written == http.getSize() && Update.end()) {
    Serial.printf("OTA success: %d bytes\n", written);
    ESP.restart();
  } else {
    Serial.printf("OTA failed: %s\n", Update.errorString());
  }
} else {
  Serial.println("Not enough partition space");
}

OTA success: 1048576 bytes
ESP32 rebooting with new firmware

Prevention

Check partition size before OTA start. Use Update.errorString() for diagnostics. Ensure stable Wi-Fi during transfer. Verify firmware binary CRC before reboot. Enable rollback for failed updates.

DodaTech engineers apply these same patterns across Doda Browser, DodaZIP, and Durga Antivirus Pro for production IoT reliability.

FAQ