The selected serial port does not exist/your board is not connected

I wanted to upload a sketch from examples and it showed me this message:
Arduino: 1.8.15 (Windows 10), Board: "Arduino Mega or Mega 2560, ATmega2560 (Mega 2560)"

C:\Program Files (x86)\Arduino\arduino-builder -dump-prefs -logger=machine -hardware C:\Program Files (x86)\Arduino\hardware -tools C:\Program Files (x86)\Arduino\tools-builder -tools C:\Program Files (x86)\Arduino\hardware\tools\avr -built-in-libraries C:\Program Files (x86)\Arduino\libraries -libraries C:\Users\Daniela\Documents\Arduino\libraries -fqbn=arduino:avr:mega:cpu=atmega2560 -vid-pid=1A86_7523 -ide-version=10815 -build-path C:\Users\Daniela\AppData\Local\Temp\arduino_build_813718 -warnings=none -build-cache C:\Users\Daniela\AppData\Local\Temp\arduino_cache_19601 -prefs=build.warn_data_percentage=75 -prefs=runtime.tools.avr-gcc.path=C:\Program Files (x86)\Arduino\hardware\tools\avr -prefs=runtime.tools.avr-gcc-7.3.0-atmel3.6.1-arduino7.path=C:\Program Files (x86)\Arduino\hardware\tools\avr -prefs=runtime.tools.arduinoOTA.path=C:\Program Files (x86)\Arduino\hardware\tools\avr -prefs=runtime.tools.arduinoOTA-1.3.0.path=C:\Program Files (x86)\Arduino\hardware\tools\avr -prefs=runtime.tools.avrdude.path=C:\Program Files (x86)\Arduino\hardware\tools\avr -prefs=runtime.tools.avrdude-6.3.0-arduino17.path=C:\Program Files (x86)\Arduino\hardware\tools\avr -verbose C:\Users\Daniela\AppData\Local\Temp\arduino_modified_sketch_980716\DHT22Default.ino

C:\Program Files (x86)\Arduino\arduino-builder -compile -logger=machine -hardware C:\Program Files (x86)\Arduino\hardware -tools C:\Program Files (x86)\Arduino\tools-builder -tools C:\Program Files (x86)\Arduino\hardware\tools\avr -built-in-libraries C:\Program Files (x86)\Arduino\libraries -libraries C:\Users\Daniela\Documents\Arduino\libraries -fqbn=arduino:avr:mega:cpu=atmega2560 -vid-pid=1A86_7523 -ide-version=10815 -build-path C:\Users\Daniela\AppData\Local\Temp\arduino_build_813718 -warnings=none -build-cache C:\Users\Daniela\AppData\Local\Temp\arduino_cache_19601 -prefs=build.warn_data_percentage=75 -prefs=runtime.tools.avr-gcc.path=C:\Program Files (x86)\Arduino\hardware\tools\avr -prefs=runtime.tools.avr-gcc-7.3.0-atmel3.6.1-arduino7.path=C:\Program Files (x86)\Arduino\hardware\tools\avr -prefs=runtime.tools.arduinoOTA.path=C:\Program Files (x86)\Arduino\hardware\tools\avr -prefs=runtime.tools.arduinoOTA-1.3.0.path=C:\Program Files (x86)\Arduino\hardware\tools\avr -prefs=runtime.tools.avrdude.path=C:\Program Files (x86)\Arduino\hardware\tools\avr -prefs=runtime.tools.avrdude-6.3.0-arduino17.path=C:\Program Files (x86)\Arduino\hardware\tools\avr -verbose C:\Users\Daniela\AppData\Local\Temp\arduino_modified_sketch_980716\DHT22Default.ino

Using board 'mega' from platform in folder: C:\Program Files (x86)\Arduino\hardware\arduino\avr

Using core 'arduino' from platform in folder: C:\Program Files (x86)\Arduino\hardware\arduino\avr

Detecting libraries used...

"C:\Program Files (x86)\Arduino\hardware\tools\avr/bin/avr-g++" -c -g -Os -w -std=gnu++11 -fpermissive -fno-exceptions -ffunction-sections -fdata-sections -fno-threadsafe-statics -Wno-error=narrowing -flto -w -x c++ -E -CC -mmcu=atmega2560 -DF_CPU=16000000L -DARDUINO=10815 -DARDUINO_AVR_MEGA2560 -DARDUINO_ARCH_AVR "-IC:\Program Files (x86)\Arduino\hardware\arduino\avr\cores\arduino" "-IC:\Program Files (x86)\Arduino\hardware\arduino\avr\variants\mega" "C:\Users\Daniela\AppData\Local\Temp\arduino_build_813718\sketch\DHT22Default.ino.cpp" -o nul

Alternatives for SimpleDHT.h: [SimpleDHT@1.0.14]

ResolveLibrary(SimpleDHT.h)

-> candidates: [SimpleDHT@1.0.14]

"C:\Program Files (x86)\Arduino\hardware\tools\avr/bin/avr-g++" -c -g -Os -w -std=gnu++11 -fpermissive -fno-exceptions -ffunction-sections -fdata-sections -fno-threadsafe-statics -Wno-error=narrowing -flto -w -x c++ -E -CC -mmcu=atmega2560 -DF_CPU=16000000L -DARDUINO=10815 -DARDUINO_AVR_MEGA2560 -DARDUINO_ARCH_AVR "-IC:\Program Files (x86)\Arduino\hardware\arduino\avr\cores\arduino" "-IC:\Program Files (x86)\Arduino\hardware\arduino\avr\variants\mega" "-IC:\Users\Daniela\Documents\Arduino\libraries\SimpleDHT" "C:\Users\Daniela\AppData\Local\Temp\arduino_build_813718\sketch\DHT22Default.ino.cpp" -o nul

"C:\Program Files (x86)\Arduino\hardware\tools\avr/bin/avr-g++" -c -g -Os -w -std=gnu++11 -fpermissive -fno-exceptions -ffunction-sections -fdata-sections -fno-threadsafe-statics -Wno-error=narrowing -flto -w -x c++ -E -CC -mmcu=atmega2560 -DF_CPU=16000000L -DARDUINO=10815 -DARDUINO_AVR_MEGA2560 -DARDUINO_ARCH_AVR "-IC:\Program Files (x86)\Arduino\hardware\arduino\avr\cores\arduino" "-IC:\Program Files (x86)\Arduino\hardware\arduino\avr\variants\mega" "-IC:\Users\Daniela\Documents\Arduino\libraries\SimpleDHT" "C:\Users\Daniela\Documents\Arduino\libraries\SimpleDHT\SimpleDHT.cpp" -o nul

Generating function prototypes...

"C:\Program Files (x86)\Arduino\hardware\tools\avr/bin/avr-g++" -c -g -Os -w -std=gnu++11 -fpermissive -fno-exceptions -ffunction-sections -fdata-sections -fno-threadsafe-statics -Wno-error=narrowing -flto -w -x c++ -E -CC -mmcu=atmega2560 -DF_CPU=16000000L -DARDUINO=10815 -DARDUINO_AVR_MEGA2560 -DARDUINO_ARCH_AVR "-IC:\Program Files (x86)\Arduino\hardware\arduino\avr\cores\arduino" "-IC:\Program Files (x86)\Arduino\hardware\arduino\avr\variants\mega" "-IC:\Users\Daniela\Documents\Arduino\libraries\SimpleDHT" "C:\Users\Daniela\AppData\Local\Temp\arduino_build_813718\sketch\DHT22Default.ino.cpp" -o "C:\Users\Daniela\AppData\Local\Temp\arduino_build_813718\preproc\ctags_target_for_gcc_minus_e.cpp"

"C:\Program Files (x86)\Arduino\tools-builder\ctags\5.8-arduino11/ctags" -u --language-force=c++ -f - --c++-kinds=svpf --fields=KSTtzns --line-directives "C:\Users\Daniela\AppData\Local\Temp\arduino_build_813718\preproc\ctags_target_for_gcc_minus_e.cpp"

Compiling sketch...

"C:\Program Files (x86)\Arduino\hardware\tools\avr/bin/avr-g++" -c -g -Os -w -std=gnu++11 -fpermissive -fno-exceptions -ffunction-sections -fdata-sections -fno-threadsafe-statics -Wno-error=narrowing -MMD -flto -mmcu=atmega2560 -DF_CPU=16000000L -DARDUINO=10815 -DARDUINO_AVR_MEGA2560 -DARDUINO_ARCH_AVR "-IC:\Program Files (x86)\Arduino\hardware\arduino\avr\cores\arduino" "-IC:\Program Files (x86)\Arduino\hardware\arduino\avr\variants\mega" "-IC:\Users\Daniela\Documents\Arduino\libraries\SimpleDHT" "C:\Users\Daniela\AppData\Local\Temp\arduino_build_813718\sketch\DHT22Default.ino.cpp" -o "C:\Users\Daniela\AppData\Local\Temp\arduino_build_813718\sketch\DHT22Default.ino.cpp.o"

Compiling libraries...

Compiling library "SimpleDHT"

"C:\Program Files (x86)\Arduino\hardware\tools\avr/bin/avr-g++" -c -g -Os -w -std=gnu++11 -fpermissive -fno-exceptions -ffunction-sections -fdata-sections -fno-threadsafe-statics -Wno-error=narrowing -MMD -flto -mmcu=atmega2560 -DF_CPU=16000000L -DARDUINO=10815 -DARDUINO_AVR_MEGA2560 -DARDUINO_ARCH_AVR "-IC:\Program Files (x86)\Arduino\hardware\arduino\avr\cores\arduino" "-IC:\Program Files (x86)\Arduino\hardware\arduino\avr\variants\mega" "-IC:\Users\Daniela\Documents\Arduino\libraries\SimpleDHT" "C:\Users\Daniela\Documents\Arduino\libraries\SimpleDHT\SimpleDHT.cpp" -o "C:\Users\Daniela\AppData\Local\Temp\arduino_build_813718\libraries\SimpleDHT\SimpleDHT.cpp.o"

Compiling core...

Using precompiled core: C:\Users\Daniela\AppData\Local\Temp\arduino_cache_19601\core\core_arduino_avr_mega_cpu_atmega2560_0c812875ac70eb4a9b385d8fb077f54c.a

Linking everything together...

"C:\Program Files (x86)\Arduino\hardware\tools\avr/bin/avr-gcc" -w -Os -g -flto -fuse-linker-plugin -Wl,--gc-sections -mmcu=atmega2560 -o "C:\Users\Daniela\AppData\Local\Temp\arduino_build_813718/DHT22Default.ino.elf" "C:\Users\Daniela\AppData\Local\Temp\arduino_build_813718\sketch\DHT22Default.ino.cpp.o" "C:\Users\Daniela\AppData\Local\Temp\arduino_build_813718\libraries\SimpleDHT\SimpleDHT.cpp.o" "C:\Users\Daniela\AppData\Local\Temp\arduino_build_813718/..\arduino_cache_19601\core\core_arduino_avr_mega_cpu_atmega2560_0c812875ac70eb4a9b385d8fb077f54c.a" "-LC:\Users\Daniela\AppData\Local\Temp\arduino_build_813718" -lm

"C:\Program Files (x86)\Arduino\hardware\tools\avr/bin/avr-objcopy" -O ihex -j .eeprom --set-section-flags=.eeprom=alloc,load --no-change-warnings --change-section-lma .eeprom=0 "C:\Users\Daniela\AppData\Local\Temp\arduino_build_813718/DHT22Default.ino.elf" "C:\Users\Daniela\AppData\Local\Temp\arduino_build_813718/DHT22Default.ino.eep"

"C:\Program Files (x86)\Arduino\hardware\tools\avr/bin/avr-objcopy" -O ihex -R .eeprom "C:\Users\Daniela\AppData\Local\Temp\arduino_build_813718/DHT22Default.ino.elf" "C:\Users\Daniela\AppData\Local\Temp\arduino_build_813718/DHT22Default.ino.hex"

Using library SimpleDHT at version 1.0.14 in folder: C:\Users\Daniela\Documents\Arduino\libraries\SimpleDHT

"C:\Program Files (x86)\Arduino\hardware\tools\avr/bin/avr-size" -A "C:\Users\Daniela\AppData\Local\Temp\arduino_build_813718/DHT22Default.ino.elf"

Sketch uses 6746 bytes (2%) of program storage space. Maximum is 253952 bytes.

Global variables use 365 bytes (4%) of dynamic memory, leaving 7827 bytes for local variables. Maximum is 8192 bytes.

C:\Program Files (x86)\Arduino\hardware\tools\avr/bin/avrdude -CC:\Program Files (x86)\Arduino\hardware\tools\avr/etc/avrdude.conf -v -patmega2560 -cwiring -PCOM3 -b115200 -D -Uflash:w:C:\Users\Daniela\AppData\Local\Temp\arduino_build_813718/DHT22Default.ino.hex:i

avrdude: Version 6.3-20190619

     Copyright (c) 2000-2005 Brian Dean, http://www.bdmicro.com/

     Copyright (c) 2007-2014 Joerg Wunsch



     System wide configuration file is "C:\Program Files (x86)\Arduino\hardware\tools\avr/etc/avrdude.conf"



     Using Port                    : COM3

     Using Programmer              : wiring

     Overriding Baud Rate          : 115200

avrdude: ser_open(): can't set com-state for "\.\COM3"

avrdude: ser_drain(): read error: The handle is invalid.

avrdude: ser_send(): write error: sorry no info avail

avrdude: stk500_send(): failed to send command to serial port

avrdude: stk500v2_ReceiveMessage(): timeout

avrdude: ser_send(): write error: sorry no info avail

avrdude: stk500_send(): failed to send command to serial port

avrdude: stk500v2_ReceiveMessage(): timeout

avrdude: ser_send(): write error: sorry no info avail

avrdude: stk500_send(): failed to send command to serial port

avrdude: stk500v2_ReceiveMessage(): timeout

avrdude: ser_send(): write error: sorry no info avail

avrdude: stk500_send(): failed to send command to serial port

avrdude: stk500v2_ReceiveMessage(): timeout

avrdude: ser_send(): write error: sorry no info avail

avrdude: stk500_send(): failed to send command to serial port

avrdude: stk500v2_ReceiveMessage(): timeout

avrdude: ser_send(): write error: sorry no info avail

avrdude: stk500_send(): failed to send command to serial port

avrdude: stk500v2_ReceiveMessage(): timeout

avrdude: stk500v2_getsync(): timeout communicating with programmer

avrdude done. Thank you.

the selected serial port

does not exist or your board is not connected

What can I do?

What does Windows Device Manager say about your board? Is it still COM3?

It shows Arduino Mega (COM3), only after i installed the Arduino Mega driver