Warning: espcomm_sync failed
error: espcomm_open failed
error: espcomm_upload_mem failed
error: espcomm_upload_mem failed “
error: espcomm_upload_mem failed”

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solutions;
First, hardware
1. Check the connection
to confirm the connection is correct,
UTXD — RXD
URXD — TXD
VCC – 3.3 V
GND – GND
2. Check to see if the serial port on ESP8266 is being used by other software stations and click on the serial port monitor. If the serial port window pops up normally, it’s ok,

If you can’t pop up, check the tool — port — (select the appropriate port).
Second, other
1. Select the corresponding development board,

2.
Press Flash (or BOOT) not to lose, and then press the reset button to release, and then click to download, flash(or BOOT) do not loose, download the end of the release.
with ESP12 activation instructions