I have written some code using the LiquidCrystal_I2C library and I get the following during compiling: "WARNING: library LiquidCrystal I2C claims to run on avr architecture(s) and may be incompatible with your current board which runs on megaavr architecture(s)." I have run another sketch with this library on this same board and did not have an issue. That being said, I attempt to upload the new sketch to the board and I get a list of avrdude errors: avrdude: jtagmkII_initialize(): Cannot locate "flash" and "boot" memories in description. avrdude: jtagmkII_recv(): checksum error. avrdude: jtagmkII_paged_load(): timeout/error communicating with programmer (status -4). avrdude: jtagmkII_recv(): checksum error. avrdude: jtagmkII_paged_load(): timeout/error communicating with programmer (status -4). Are these related somehow? Do I need to use a different I2C LCD library? Do I need to wipe the memory of the board prior to uploading the new software? Thanks ahead of time for your assistance.

AVRdude is about uploading, so the I2C library is not the cause for those errors. Think you have to check the board selected.

Hi @jpfrancis690. I'm going to ask you to provide the full verbose output from an upload attempt. :red_exclamation_mark: This procedure is not intended to solve the problem. The purpose is to gather more information. Please do this: Select File > Preferences... (or Arduino IDE > Settings... for macOS users) from the Arduino IDE menus. The "Preferences" dialog will open. Uncheck the box next to Show verbose output during: ☑ compile in the "Preferences" dialog. Check the box next to Show verbose output during: ☐ upload. Click the "OK" button. The "Preferences" dialog will close. Attempt an upload, as you did before. Wait for the upload to fail. You will see an "Upload error: ..." notification at the bottom right corner of the Arduino IDE window. Click the "COPY ERROR MESSAGES" button on that notification. Open a reply here on this forum topic by clicking the "Reply" button. Click the icon on the post composer toolbar. This will add the forum's code block markup (```) to your reply to make sure the error messages are correctly formatted. [Code block icon on toolbar] Press the Ctrl+V keyboard shortcut (Command+V for macOS users). This will paste the error output from the upload into the code block. Move the cursor outside of the code block markup before you add any additional text to your reply. Click the "Reply" button to publish the post.

WARNING: library LiquidCrystal I2C claims to run on avr architecture(s) and may be incompatible with your current board which runs on megaavr architecture(s). Sketch uses 15199 bytes (30%) of program storage space. Maximum is 49152 bytes. Global variables use 622 bytes (10%) of dynamic memory, leaving 5522 bytes for local variables. Maximum is 6144 bytes. Performing 1200-bps touch reset on serial port COM4 "C:\Users\john.francis.PLASTOCOR\AppData\Local\Arduino15\packages\arduino\tools\avrdude\6.3.0-arduino17/bin/avrdude" "-CC:\Users\john.francis.PLASTOCOR\AppData\Local\Arduino15\packages\arduino\tools\avrdude\6.3.0-arduino17/etc/avrdude.conf" -v -patmega4809 -cjtag2updi -PCOM4 -b115200 -e -D "-Uflash:w:C:\Users\john.francis.PLASTOCOR\AppData\Local\arduino\sketches\CC9926F80742956021F8C4C54ED82FD9/Precision_Dispenser_no_keyboard_sketch_aug19a.ino.hex:i" "-Ufuse2:w:0x01:m" "-Ufuse5:w:0xC9:m" "-Ufuse8:w:0x00:m" {upload.extra_files} 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:\Users\john.francis.PLASTOCOR\AppData\Local\Arduino15\packages\arduino\tools\avrdude\6.3.0-arduino17/etc/avrdude.conf" Using Port : COM4 Using Programmer : jtag2updi Overriding Baud Rate : 115200 JTAG ICE mkII sign-on message: Communications protocol version: 1 M_MCU: boot-loader FW version: 1 firmware version: 1.07 hardware version: 1 S_MCU: boot-loader FW version: 1 firmware version: 6.07 hardware version: 1 Serial number: 00:00:00:00:00:00 Device ID: JTAGICE mkII AVR Part : ATmega4809 Chip Erase delay : 0 us PAGEL : P00 BS2 : P00 RESET disposition : dedicated RETRY pulse : SCK serial program mode : yes parallel program mode : yes Timeout : 0 StabDelay : 0 CmdexeDelay : 0 SyncLoops : 0 ByteDelay : 0 PollIndex : 0 PollValue : 0x00 Memory Detail : Block Poll Page Polled Memory Type Mode Delay Size Indx Paged Size Size #Pages MinW MaxW ReadBack ----------- ---- ----- ----- ---- ------ ------ ---- ------ ----- ----- --------- signature 0 0 0 0 no 3 0 0 0 0 0x00 0x00 prodsig 0 0 0 0 no 61 61 0 0 0 0x00 0x00 fuses 0 0 0 0 no 9 0 0 0 0 0x00 0x00 fuse0 0 0 0 0 no 1 0 0 0 0 0x00 0x00 fuse1 0 0 0 0 no 1 0 0 0 0 0x00 0x00 fuse2 0 0 0 0 no 1 0 0 0 0 0x00 0x00 fuse4 0 0 0 0 no 1 0 0 0 0 0x00 0x00 fuse5 0 0 0 0 no 1 0 0 0 0 0x00 0x00 fuse6 0 0 0 0 no 1 0 0 0 0 0x00 0x00 fuse7 0 0 0 0 no 1 0 0 0 0 0x00 0x00 fuse8 0 0 0 0 no 1 0 0 0 0 0x00 0x00 lock 0 0 0 0 no 1 0 0 0 0 0x00 0x00 data 0 0 0 0 no 0 0 0 0 0 0x00 0x00 usersig 0 0 0 0 no 64 64 0 0 0 0x00 0x00 flash 0 0 0 0 no 49152 128 0 0 0 0x00 0x00 eeprom 0 0 0 0 no 256 64 0 0 0 0x00 0x00 Programmer Type : JTAGMKII_PDI Description : JTAGv2 to UPDI bridge M_MCU hardware version: 1 M_MCU firmware version: 1.07 S_MCU hardware version: 1 S_MCU firmware version: 6.07 Serial number: 00:00:00:00:00:00 Vtarget : 5.0 V avrdude: jtagmkII_initialize(): Cannot locate "flash" and "boot" memories in description avrdude: AVR device initialized and ready to accept instructions Reading | ################################################## | 100% 0.27s avrdude: Device signature = 0x1e9651 (probably m4809) avrdude: erasing chip avrdude: reading input file "C:\Users\john.francis.PLASTOCOR\AppData\Local\arduino\sketches\CC9926F80742956021F8C4C54ED82FD9/Precision_Dispenser_no_keyboard_sketch_aug19a.ino.hex" avrdude: writing flash (15200 bytes): Writing | ################################################## | 100% 11.17s avrdude: 15200 bytes of flash written avrdude: verifying flash memory against C:\Users\john.francis.PLASTOCOR\AppData\Local\arduino\sketches\CC9926F80742956021F8C4C54ED82FD9/Precision_Dispenser_no_keyboard_sketch_aug19a.ino.hex: avrdude: load data flash data from input file C:\Users\john.francis.PLASTOCOR\AppData\Local\arduino\sketches\CC9926F80742956021F8C4C54ED82FD9/Precision_Dispenser_no_keyboard_sketch_aug19a.ino.hex: avrdude: input file C:\Users\john.francis.PLASTOCOR\AppData\Local\arduino\sketches\CC9926F80742956021F8C4C54ED82FD9/Precision_Dispenser_no_keyboard_sketch_aug19a.ino.hex contains 15200 bytes avrdude: reading on-chip flash data: Reading | ###########avrdude: jtagmkII_recv(): checksum error avrdude: jtagmkII_paged_load(): timeout/error communicating with programmer (status -4) ###########avrdude: jtagmkII_recv(): checksum error avrdude: jtagmkII_paged_load(): timeout/error communicating with programmer (status -4) ############################ | 100% 2.30s avrdude: verifying ... avrdude: 15200 bytes of flash verified avrdude: reading input file "0x01" avrdude: writing fuse2 (1 bytes): Writing | ################################################## | 100% 0.00s avrdude: 1 bytes of fuse2 written avrdude: verifying fuse2 memory against 0x01: avrdude: load data fuse2 data from input file 0x01: avrdude: input file 0x01 contains 1 bytes avrdude: reading on-chip fuse2 data: Reading | ################################################## | 100% 0.00s avrdude: verifying ... avrdude: 1 bytes of fuse2 verified avrdude: reading input file "0xC9" avrdude: writing fuse5 (1 bytes): Writing | ################################################## | 100% 0.01s avrdude: 1 bytes of fuse5 written avrdude: verifying fuse5 memory against 0xC9: avrdude: load data fuse5 data from input file 0xC9: avrdude: input file 0xC9 contains 1 bytes avrdude: reading on-chip fuse5 data: Here you go done as per your instructions.

Would it also help to up load the sketch also?

It is possible for a short or external circuitry connected to the Arduino board to interfere with the upload process, causing this type of upload error. Make sure the board is not sitting on anything conductive that could short the contacts on the bottom of the board. Do a careful visual examination to make sure there isn't any conductive debris (e.g., loose beads of solder, strands of wire, or component leads) on either side of the board, or on the surface the board is sitting on. If you have a shield or any external circuitry or components connected to your Arduino board, try this experiment: Disconnect the USB cable of the Arduino board from your computer. Disconnect any shields, modules, external circuitry, etc. from your board. Make sure to remove any connections to your LCD display. Connect the Arduino board to your computer with a USB cable. Now try uploading a sketch to the board again. Does the upload now succeed? This experiment will determine whether the upload error was caused by interference from your external circuitry. If so, you can then focus your attention on identifying the specific problem with the circuit and resolving it.

So, I have the Nano Every installed into a DIN rail screw terminal board which is installed in a control cabinet for a stepper motor (See pictures). When the laptop I am using is not connected, the board is powered from an internal power supply. So I have previously uploaded sketches to test various functions and have had no problems but now I am at the next to final stage of testing of functions and have run into this load error. I will try the what you have stated and report back the results. [image] [image]

I have completely removed the Nano from the DIN rail holder and with it standing by itself, I attempted to load again. I got the same error messages as the last time. WARNING: library LiquidCrystal I2C claims to run on avr architecture(s) and may be incompatible with your current board which runs on megaavr architecture(s). Sketch uses 15199 bytes (30%) of program storage space. Maximum is 49152 bytes. Global variables use 622 bytes (10%) of dynamic memory, leaving 5522 bytes for local variables. Maximum is 6144 bytes. Performing 1200-bps touch reset on serial port COM4 "C:\Users\john.francis.PLASTOCOR\AppData\Local\Arduino15\packages\arduino\tools\avrdude\6.3.0-arduino17/bin/avrdude" "-CC:\Users\john.francis.PLASTOCOR\AppData\Local\Arduino15\packages\arduino\tools\avrdude\6.3.0-arduino17/etc/avrdude.conf" -v -patmega4809 -cjtag2updi -PCOM4 -b115200 -e -D "-Uflash:w:C:\Users\john.francis.PLASTOCOR\AppData\Local\arduino\sketches\CC9926F80742956021F8C4C54ED82FD9/Precision_Dispenser_no_keyboard_sketch_aug19a.ino.hex:i" "-Ufuse2:w:0x01:m" "-Ufuse5:w:0xC9:m" "-Ufuse8:w:0x00:m" {upload.extra_files} 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:\Users\john.francis.PLASTOCOR\AppData\Local\Arduino15\packages\arduino\tools\avrdude\6.3.0-arduino17/etc/avrdude.conf" Using Port : COM4 Using Programmer : jtag2updi Overriding Baud Rate : 115200 JTAG ICE mkII sign-on message: Communications protocol version: 1 M_MCU: boot-loader FW version: 1 firmware version: 1.07 hardware version: 1 S_MCU: boot-loader FW version: 1 firmware version: 6.07 hardware version: 1 Serial number: 00:00:00:00:00:00 Device ID: JTAGICE mkII AVR Part : ATmega4809 Chip Erase delay : 0 us PAGEL : P00 BS2 : P00 RESET disposition : dedicated RETRY pulse : SCK serial program mode : yes parallel program mode : yes Timeout : 0 StabDelay : 0 CmdexeDelay : 0 SyncLoops : 0 ByteDelay : 0 PollIndex : 0 PollValue : 0x00 Memory Detail : Block Poll Page Polled Memory Type Mode Delay Size Indx Paged Size Size #Pages MinW MaxW ReadBack ----------- ---- ----- ----- ---- ------ ------ ---- ------ ----- ----- --------- signature 0 0 0 0 no 3 0 0 0 0 0x00 0x00 prodsig 0 0 0 0 no 61 61 0 0 0 0x00 0x00 fuses 0 0 0 0 no 9 0 0 0 0 0x00 0x00 fuse0 0 0 0 0 no 1 0 0 0 0 0x00 0x00 fuse1 0 0 0 0 no 1 0 0 0 0 0x00 0x00 fuse2 0 0 0 0 no 1 0 0 0 0 0x00 0x00 fuse4 0 0 0 0 no 1 0 0 0 0 0x00 0x00 fuse5 0 0 0 0 no 1 0 0 0 0 0x00 0x00 fuse6 0 0 0 0 no 1 0 0 0 0 0x00 0x00 fuse7 0 0 0 0 no 1 0 0 0 0 0x00 0x00 fuse8 0 0 0 0 no 1 0 0 0 0 0x00 0x00 lock 0 0 0 0 no 1 0 0 0 0 0x00 0x00 data 0 0 0 0 no 0 0 0 0 0 0x00 0x00 usersig 0 0 0 0 no 64 64 0 0 0 0x00 0x00 flash 0 0 0 0 no 49152 128 0 0 0 0x00 0x00 eeprom 0 0 0 0 no 256 64 0 0 0 0x00 0x00 Programmer Type : JTAGMKII_PDI Description : JTAGv2 to UPDI bridge M_MCU hardware version: 1 M_MCU firmware version: 1.07 S_MCU hardware version: 1 S_MCU firmware version: 6.07 Serial number: 00:00:00:00:00:00 Vtarget : 5.0 V avrdude: jtagmkII_initialize(): Cannot locate "flash" and "boot" memories in description avrdude: AVR device initialized and ready to accept instructions Reading | ################################################## | 100% 0.27s avrdude: Device signature = 0x1e9651 (probably m4809) avrdude: erasing chip avrdude: reading input file "C:\Users\john.francis.PLASTOCOR\AppData\Local\arduino\sketches\CC9926F80742956021F8C4C54ED82FD9/Precision_Dispenser_no_keyboard_sketch_aug19a.ino.hex" avrdude: writing flash (15200 bytes): Writing | ################################################## | 100% 11.16s avrdude: 15200 bytes of flash written avrdude: verifying flash memory against C:\Users\john.francis.PLASTOCOR\AppData\Local\arduino\sketches\CC9926F80742956021F8C4C54ED82FD9/Precision_Dispenser_no_keyboard_sketch_aug19a.ino.hex: avrdude: load data flash data from input file C:\Users\john.francis.PLASTOCOR\AppData\Local\arduino\sketches\CC9926F80742956021F8C4C54ED82FD9/Precision_Dispenser_no_keyboard_sketch_aug19a.ino.hex: avrdude: input file C:\Users\john.francis.PLASTOCOR\AppData\Local\arduino\sketches\CC9926F80742956021F8C4C54ED82FD9/Precision_Dispenser_no_keyboard_sketch_aug19a.ino.hex contains 15200 bytes avrdude: reading on-chip flash data: Reading | #########avrdude: jtagmkII_recv(): checksum error avrdude: jtagmkII_paged_load(): timeout/error communicating with programmer (status -4) ################################avrdude: jtagmkII_recv(): checksum error avrdude: jtagmkII_paged_load(): timeout/error communicating with programmer (status -4) ######### | 100% 2.37s avrdude: verifying ... avrdude: 15200 bytes of flash verified avrdude: reading input file "0x01" avrdude: writing fuse2 (1 bytes): Writing | ################################################## | 100% 0.01s avrdude: 1 bytes of fuse2 written avrdude: verifying fuse2 memory against 0x01: avrdude: load data fuse2 data from input file 0x01: avrdude: input file 0x01 contains 1 bytes avrdude: reading on-chip fuse2 data: Reading | ################################################## | 100% 0.00s avrdude: verifying ... avrdude: 1 bytes of fuse2 verified avrdude: reading input file "0xC9" avrdude: writing fuse5 (1 bytes): Writing | ################################################## | 100% 0.00s avrdude: 1 bytes of fuse5 written avrdude: verifying fuse5 memory against 0xC9: avrdude: load data fuse5 data from input file 0xC9: avrdude: input file 0xC9 contains 1 bytes avrdude: reading on-chip fuse5 data: Reading | ################################################## | 100% 0.00s avrdude: verifying ... avrdude: 1 bytes of fuse5 verified avrdude: reading input file "0x00" avrdude: writing fuse8 (1 bytes): Writing | ################################################## | 100% 0.01s avrdude: 1 bytes of fuse8 written avrdude: verifying fuse8 memory against 0x00: avrdude: load data fuse8 data from input file 0x00: avrdude: input file 0x00 contains 1 bytes avrdude: reading on-chip fuse8 data: Reading | ################################################## | 100% 0.00s avrdude: verifying ... avrdude: 1 bytes of fuse8 verified avrdude done. Thank you. Could it be a board setting that I am missing?

Looking through the Tools drop-down menu I noticed that the programmer that is listed is different than the one listed in the error message (see screen shot below); [Screenshot 2026-08-26 160015] Could this be a factor? This is the only choice I can select.

It looks like the upload was successful. Did Arduino IDE show an "Upload error: ... notification, like this?: The message might be "Upload error: ...: [screenshot of error notification] Or did it instead display a "Done uploading." notification?: [screenshot of success notification] If the latter, the the upload was successful. The checksum error that occurred when reading back the data from flash is concerning, but it appears it was able to recover from that. And the verification was successful, so this doesn't indicate the uploaded program was corrupted. I'm not sure what exactly could cause the checksum error. You could try a different USB cable just to make sure it isn't being caused by a damaged or defective cable. It might indicate that the ATmega4809 microcontroller on your board has suffered permanent physical damage. It would be worth procuring a replacement board. That is handy to have regardless, especially since your board is going to be permanently incorporated into your equipment. A spare board would allow you to perform an experiment checking whether the checksum error is specific to one board, or occurs with both. If the error is specific to one board, that would support my hypothesis of a damaged board. If the error instead occurs with the fresh board as well, this would indicate a problem with some component in the system other than the board.

I have ordered new boards and new cables to see if this makes a difference. I will let you know if the checksum goes away.

Nano Every AVR incompatibility warning

Official Hardware Nano Family Nano Every

ptillisch August 31, 2026, 6:48pm 13

I only found one other post that contains the distinctive "avrdude: jtagmkII_recv(): checksum error" error message you encountered:

Topic		Replies	Views
Can't upload anything on Arduino Nano Every Nano Every	26	3198	January 15, 2024
Property 'upload.tool.serial' is undefined Uploading	24	253	October 9, 2026
IDE writing fails 1/2 the time Uploading	3	123	July 13, 2026
Errors in uploading in arduino nano type c development board Uploading	12	238	December 15, 2025
Error Message Nano Every Nano Every	15	582	July 7, 2024

Nano Every AVR incompatibility warning

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