Upload error

[chankalun]

Hello, I am trying to use the library with an arduino mega, ESP8266 and FTDI USB to TTL Converter, and received an error as below. Can you advice please?

`Sketch uses 386044 bytes (77%) of program storage space. Maximum is 499696 bytes. Global variables use 28736 bytes (35%) of dynamic memory, leaving 53184 bytes for local variables. Maximum is 81920 bytes. esptool.py v2.6 2.6 esptool.py v2.6 Serial port /dev/cu.usbmodem141101 Connecting......................................____Traceback (most recent call last): File "/Users/username/Library/Arduino15/packages/esp8266/hardware/esp8266/2.5.2/tools/upload.py", line 25, in esptool.main(fakeargs) File "/Users/username/Library/Arduino15/packages/esp8266/hardware/esp8266/2.5.2/tools/esptool/esptool.py", line 2653, in main esp.connect(args.before) File "/Users/username/Library/Arduino15/packages/esp8266/hardware/esp8266/2.5.2/tools/esptool/esptool.py", line 468, in connect raise FatalError('Failed to connect to %s: %s' % (self.CHIP_NAME, last_error)) esptool.FatalError: Failed to connect to ESP8266: Timed out waiting for packet header esptool.FatalError: Failed to connect to ESP8266: Timed out waiting for packet header

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