Code for Wemos D1 mini won't compile

Three years ago I made a device that uses a mini D1 R2, an RTC, an SD card, and U8G2 graphics. It was working. Two days ago I installed esp8266, ver.3.0.2. Noe I get compiler errors. Thinking it might have to do with the SD card or graphics, I wrote a very simple sketch that just reads the RTC and prints the result to the serial monitor. I get the same errors. I tried other versions of wemos cards with same result.

Non verbose (down load) error file is listed below. I don't know what it tells me, so any help would be greatly appreciated.

Arduino: 1.8.9 (Windows 10), Board: "LOLIN(WEMOS) D1 R2 & mini, 80 MHz, Flash, Disabled (new aborts on oom), Disabled, All SSL ciphers (most compatible), 32KB cache + 32KB IRAM (balanced), Use pgm_read macros for IRAM/PROGMEM, 4MB (FS:2MB OTA:~1019KB), v2 Lower Memory, Disabled, None, Only Sketch, 921600"

Traceback (most recent call last):

File "C:\Users\Richard\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\3.0.2/tools/", line 211, in


File "C:\Users\Richard\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\3.0.2/tools/", line 192, in main


File "C:\Users\Richard\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\3.0.2/tools/", line 187, in wrapper

write_bin(out=out, args=args, **kwargs)

File "C:\Users\Richard\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\3.0.2/tools/", line 75, in write_bin

[size, addr] = get_segment_size_addr(elf, segment, args.path)

File "C:\Users\Richard\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\3.0.2/tools/", line 47, in get_segment_size_addr

p = subprocess.Popen([path + '/xtensa-lx106-elf-objdump', '-h', '-j', segment,  elf], stdout=subprocess.PIPE, universal_newlines=True )

File "D:\obj\Windows-Release\37win32_Release\msi_python\zip_win32\", line 775, in init

File "D:\obj\Windows-Release\37win32_Release\msi_python\zip_win32\", line 1178, in _execute_child

FileNotFoundError: [WinError 2] The system cannot find the file specified

exit status 1
Error compiling for board LOLIN(WEMOS) D1 R2 & mini.

This report would have more information with
"Show verbose output during compilation"
option enabled in File -> Preferences.

Simple WeMos sketch that generates above error mesages.

// Uses WeMos D1 mini on COM8

#include <Wire.h>

#include <RTClib.h>

RTC_DS3231 rtc;

int oldMinute;
int oldHour;
int oldDay;
int oldMonth;

int nowHour;
int nowMinute;
int nowDay;
int nowMonth;
int nowSecond;

int I;

void setup() // ****************start of setup *****************

while (!Serial) {
// wait for serial port to connect.

if (! rtc.begin())
Serial.println("Couldn't find RTC");
while (1);

// This line sets the RTC with an explicit date & time, for example to set
// April 31, 2019 at 10:10 am you would call:
// (year, month, day-of-month, hour, minute, second)

rtc.adjust(DateTime(2021, 11, 1, 10, 5, 0));
DateTime now =;

// set initial hour
oldMinute = now.minute();
oldHour = now.hour();
oldDay =;
oldMonth = now.month();

Serial.print("initial value of month, day, and hour = ");
Serial.print(", ");
Serial.print(", ");
Serial.print(", ");

} //*************** end of setup()********************

void loop() // **START OF LOOP

  DateTime now =;
  nowHour = now.hour();
  nowMinute = now.minute();
  nowDay =;
  nowMonth = now.month();
  nowSecond = now.second();

  if(nowMinute != oldMinute)
  Serial.print("current month, day, hour, minute and second: ");
  Serial.print("  ");
  Serial.print("  ");
  Serial.print("  ");
   Serial.print("  ");

 oldMinute = nowMinute;


Please post that sketch

what is "D:\obj\Windows-Release?

please RE-edit your first posting with the sketch by using this method:

click on the pencil-icon below your first posting to activate edit-mode.
mark all the code and delete it

Then You should post code by using code-tags
There is an automatic function for doing this in the Arduino-IDE
just three steps

  1. press Ctrl-T for autoformatting your code
  2. do a rightclick with the mouse and choose "copy for forum"
  3. paste clipboard into write-window of a posting

best regards Stefan

the code doesn't matter. the toolchain is broken

Is there a way I can fix it?


setting up a complete new installation of the arduino-IDE actual version 1.8.16
and re-install all additional libraries

second version:
unzipping a portable installation of the Arduino-IDE
and copying your folder "library" from your original installation into the subfolder "portable\sketchbook"

and adding the additional board-url.
best regards Stefan

I asked

It's having problems in a Python (.py) program in the Arduino esp8266 3.0.2 installation. If reinstalling the ESP8266 support doesn't help, I would try reinstalling Python.


That’s what I figured when I looked at the error log. The previous version of ESP8266 I was using (Jan 2019 according to the dates on some sketches) worked just fine. I tried reinstalling ESP8266 to an earlier version. But I seemed to get ver. 3.0.2 again. I’ll try that approach again, and reinstall Python..

Thanks for your suggestion.