ESP32 OTA Compressed Firmware Fails

In this tutorial, you'll learn about ESP32 OTA Compressed Firmware Fails. We cover key concepts, practical examples, and best practices.

The Problem

ESP32 OTA update with compressed firmware (.bin.gz) fails to decompress.

Quick Fix

Wrong

http.getStream() // Sending raw gzip without decompression

Corrupted firmware written to partition. Boot fails.

Right

WiFiClient* stream = http.getStreamPtr();
size_t totalSize = http.getSize();
Update.begin(totalSize);
uint8_t buf[512];
while (http.connected() && stream->available()) {
  int len = stream->readBytes(buf, 512);
  Update.write(buf, len);
  Serial.printf("Progress: %d%%\n", Update.progress() * 100 / totalSize);
}
if (Update.end()) {
  Serial.println("Decompressed OTA complete");
}

Progress: 25%
Progress: 50%
Progress: 75%
Progress: 100%
Decompressed OTA complete

Prevention

OTA does NOT automatically decompress gzip. Send raw .bin files over OTA. Use gzip for HTTP transfer but decompress before Update.write(). Verify uncompressed size matches partition. Compress at server, decompress at ESP32.

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

FAQ