Writing on Serial COM Port through CMD - Permission Denied?

Question

I am trying to flash the Micropython Firmware on my ESP32 via USB via the CMD (admin mode) on Windows 8. This is what im getting:

C:\Users\Administrator\Downloads>esptool.py --port COM3  --baud 460800 write_flash --flash_size=detect 0 esp32-20190207-v1.10-54-g43a894fb4.bin
esptool.py v2.6
Serial port COM3
Traceback (most recent call last):
  File "C:\Program Files\Python36\Scripts\esptool.py-script.py", line 11, in <module>
    load_entry_point('esptool==2.6', 'console_scripts', 'esptool.py')()
  File "c:\program files\python36\lib\site-packages\esptool.py", line 2952, in _main
    main()
  File "c:\program files\python36\lib\site-packages\esptool.py", line 2646, in main
    esp = ESPLoader.detect_chip(each_port, initial_baud, args.before, args.trace)
  File "c:\program files\python36\lib\site-packages\esptool.py", line 258, in detect_chip
    detect_port = ESPLoader(port, baud, trace_enabled=trace_enabled)
  File "c:\program files\python36\lib\site-packages\esptool.py", line 222, in __init__
    self._port = serial.serial_for_url(port)
  File "c:\program files\python36\lib\site-packages\serial\__init__.py", line 88, in serial_for_url
    instance.open()
  File "c:\program files\python36\lib\site-packages\serial\serialwin32.py", line 62, in open
    raise SerialException("could not open port {!r}: {!r}".format(self.portstr, ctypes.WinError()))
serial.serialutil.SerialException: could not open port 'COM3': PermissionError(13, 'Zugriff verweigert*', None, 5)

• Zugriff verweigert == Permission denied

What can i do here? Im not sure if this is an error on the OS side or on the script - i dont know what could possibly deny me permission when im using admin CMD?

• i read through this: https://stackoverflow.com/questions/6105182/error-while-opening-port-in-python but turning the COM port off and on did not help.