Upload Failed
Espressif ESP32
Severity:What Does This Error Mean?
ESP32 upload failed means esptool could not connect to the chip to flash firmware. Hold the BOOT button on the board while clicking Upload in the IDE, then release it once the upload percentage starts increasing.
Affected Models
- ESP32-DevKitC
- ESP32-WROOM-32
- ESP32-S3
- ESP32-C3
- All ESP32 variants
Common Causes
- Chip not entering bootloader mode — BOOT button not held during upload
- Wrong COM port selected in the IDE
- Missing or outdated USB-to-serial driver (CP2102, CH340)
- Upload speed too high for the USB cable or chip variant
- Another program (Serial Monitor) has the COM port open