Arduino IDE on Apple Silicon Mac: All 19 Cores Need Rosetta

Arduino IDE 2.3.10 for Apple silicon is a native app. I mounted the arm64 disk image on this Mac mini (M4, macOS 26.4.1) and Gatekeeper accepted it as notarized Developer ID software from Arduino SA. Then I asked the same backend it bundles, arduino-cli 1.5.1, to compile the two-line Blink sketch for an Uno, and got this:

$ arduino-cli compile -b arduino:avr:uno Blink
Error during build: fork/exec .../tools/avr-gcc/7.3.0-atmel3.6.1-arduino7/bin/avr-g++:
bad CPU type in executable

This Mac has never had Rosetta installed, so every Intel binary fails straight away and nothing hides it. The IDE is native. Almost everything it runs to build and upload a sketch is not. The usual answer on Arduino's forum is to install Rosetta, and it works. The catch is the date: Apple's developer documentation says Rosetta "will be available through macOS 27" as a general-purpose tool. After that, Apple keeps only a subset aimed at older games.

So I checked which boards build on an Apple silicon Mac without Rosetta, and what the rest would need. No board was plugged in. Compiling needs no hardware, and the Intel upload tools fail before they look for a port.

The IDE itself is fine

Of the 30 Mach-O files in Arduino IDE.app, 27 are arm64. The three Intel files are a macos-trash helper and two serial-port addons in the bundled Cortex-Debug plugin. arduino-cli, the language server, clangd and the serial-monitor tool are all arm64. If the window opens and the compile fails, the IDE isn't the problem.

19 of 19 Arduino cores still need an Intel tool

The board cores are where the Intel binaries come from. Each core's entry in the board-manager index lists the tools it needs, with one download per host platform. I parsed the three indexes most people have installed: Arduino's own package_index.json, Espressif's ESP32 index and Earle Philhower's RP2040 index, all fetched on 2026-10-21. For each core I took the newest non-deprecated version and checked whether every tool has a macOS arm64 build.

Of the 32 cores, 13 ship an arm64 compiler for macOS, and 7 have every listed tool in arm64. None of those 7 is from Arduino. Of Arduino's own 19 arduino:* cores, 15 have an Intel-only compiler. That includes AVR (Uno R3, Nano, Mega), megaAVR, SAM, SAMD, both Renesas cores (Uno R4) and all eight Mbed cores. The other 4, the three Zephyr cores and Arduino's ESP32 fork, have arm64 compilers but still pull in at least one Intel-only uploader: bossac, dfu-util, openocd or esptool 4.5.1.

Porting them is clearly possible. The same avr-gcc 7.3.0 and ctags have aarch64-linux-gnu builds, so a Raspberry Pi gets ARM binaries. The macOS entries are x86_64-apple-darwin14 and x86_64-apple-darwin only. In 2024 an Arduino maintainer wrote on the IDE tracker that once arm64 builds land in the index, the IDE will use them automatically.

The Intel binary every sketch hits: ctags

The two boards with arm64 compilers didn't get much further. A Pico 2 W build failed after 1.77 seconds, and an ESP32-C6 build failed the same way:

$ arduino-cli compile -b rp2040:rp2040:rpipico2w Blink
Error during build: fork/exec .../packages/builtin/tools/ctags/5.8-arduino11/ctags:
bad CPU type in executable

Before compiling a .ino file, Arduino runs a patched Exuberant Ctags to generate function prototypes, which is why you can call a function above its definition. It's a "builtin" tool, so no board core can swap it. It is x86_64 only, and its repository was last released as 5.8-arduino11 on 2017-01-09. The same error shows up on Arduino's forum from an M4 MacBook Pro owner with an ESP32-C6 in August 2025.

Building it from source fails on a current SDK. The unpatched tree stops at MacOSX.sdk/usr/include/dirent.h:84:2: error: use of undeclared identifier 'unused'. An open pull request, arduino/ctags#24, fixes the build:

git clone https://github.com/arduino/ctags.git && cd ctags
gh pr diff 24 --repo arduino/ctags | git apply
./configure && make
file ctags        # Mach-O 64-bit executable arm64
cp ctags ~/Library/Arduino15/packages/builtin/tools/ctags/5.8-arduino11/ctags

With that 301 KB binary in place, both boards compiled on an Apple silicon Mac with no Rosetta installed. The Pico 2 W Blink came out at 309,872 bytes in 14 seconds from a clean build. The ESP32-C6 build was 262,354 bytes and the ESP32-S3 build 288,462. To check that prototype generation still works, I also compiled a sketch that calls two functions defined below loop(), and it built. Both upload paths also ran natively: Espressif's esptool 5.3.1 and the Pico core's Python uploader started and stopped only when they couldn't find a board.

On the ctags issue, open since December 2023, GitHub user me-no-dev asked on 2026-10-12 for an Apple silicon release. The Arduino team member who replied said the pull request "targets the issue but we need to setup a proper CI in the meantime." No release date has been given.

Uno and Nano: the compiler can be swapped, the uploader blocks

AVR boards fail one step earlier, at avr-gcc. Paul Stoffregen, who makes the Teensy boards, published an experimental arm64 build of the same avr-gcc 7.3.0 in May. On the toolchain's open Apple silicon issue he wrote that Teensy package 1.62 now ships it. I put it in place of Arduino's avr-gcc folder, alongside the arm64 ctags. Blink for the Uno compiled to 924 bytes, Blink for the Nano did too, and the prototype test sketch came out at 1,982 bytes.

The upload did not work:

Failed uploading: cannot execute upload tool: fork/exec
.../tools/avrdude/8.0.0-arduino1/bin/avrdude: bad CPU type in executable

Homebrew's avrdude 8.3 is built for arm64 on Tahoe, and one user posted a script on the same issue that links Homebrew binaries over Arduino's. I didn't test either. Swapping files in ~/Library/Arduino15 by hand is a workaround, too: the next core update overwrites them.

What to do today

Install Rosetta. The text of Arduino's help article on this error explains why the IDE never asks: macOS shows its Rosetta install dialog when you open an Intel app, but not when an Intel tool runs as a subprocess, so the first sign is a failed compile. One command fixes it:

softwareupdate --install-rosetta --agree-to-license

That covers every Arduino core through macOS 27. If you'd rather not install Rosetta, or you're choosing a board for a Mac you'll keep past macOS 27, RP2040/RP2350 boards on Philhower's core and ESP32 boards on Espressif's core 3.x are the two families whose compiler and uploader already run natively. Either way you still need the ctags build above. Arduino's own boards depend on Arduino publishing arm64 tools.

Which board to buy for a Mac

As an Amazon Associate I earn from qualifying purchases. Prices are Amazon US as of 2026-10-21, read with a New York delivery address, and all three listings had an add-to-cart button. I don't own any of these boards. What follows is about their toolchains, which I tested, plus spec pages and owner reports.

• Least Rosetta-dependent: a Freenove Raspberry Pi Pico 2 W with headers soldered ($18.95). Its whole toolchain is arm64 apart from ctags. One caveat: the first RP2350 silicon (stepping A2) has the E9 GPIO erratum, where inputs latch around 2.2 V. Raspberry Pi's July 2025 post says the A4 stepping fixes it and that remaining A2 inventory was withdrawn. The listing doesn't say which stepping it ships, so check the marking on the chip (RP2350A0A4) if you rely on pull-downs.
• The official board most tutorials use: the Arduino UNO R4 Minima ($19.99). It needs Rosetta for its compiler, bossac and dfu-util. Owners on Arduino's forum describe dfu-util upload failures that a double-tap of the reset button fixes. Those reports aren't Mac-specific.
• A starter kit: the ELEGOO UNO R3 Super Starter Kit ($45.99, 16,619 ratings). The board is an Uno R3 clone, so it uses the AVR toolchain: install Rosetta first, or your first Blink fails the way this M1 owner's did in 2022. Arduino's maintainer replied there that he wasn't sure "what the prospects will be" for native builds. Nearly four years later, that is still where things stand.

If the board shows up but no serial port does, that's a different problem. My USB-to-serial adapter guide covers which chips macOS drives out of the box. The same Rosetta question has come up across the maker tools I've tested on this machine: CNC software for Mac (Candle is still Intel-only) and logic analyzer apps (three of five). If your error says exec format error rather than bad CPU type, that one usually isn't about the CPU.

Update 2026-10-22: Garmin took the opposite route to Arduino's help article. Instead of telling users to install Rosetta, the Garmin Express 7.29.3 installer runs softwareupdate --install-rosetta --agree-to-license itself as root, and fails the whole install if that step fails. Details in Garmin Express on Mac.

FAQ

Does Arduino IDE work on M1, M2, M3 and M4 Macs?

Yes, the IDE itself does: Arduino IDE 2.3.10 has a native, notarized Apple silicon build. Compiling and uploading are the problem. They run tools from the board core, and every Arduino-made core includes at least one Intel-only tool, so you need Rosetta (softwareupdate --install-rosetta --agree-to-license). Apple says Rosetta remains available for apps through macOS 27.

Why does Arduino IDE say "bad CPU type in executable" on my Mac?

The IDE started an Intel-only tool, such as avr-gcc, arm-none-eabi-gcc, avrdude, bossac or the builtin ctags, on an Apple silicon Mac without Rosetta. macOS doesn't show its Rosetta install dialog when an app launches an Intel tool in the background, so you have to install Rosetta from Terminal. If the path in the error contains avr-gcc 4.8.1, the cause is different: that compiler is 32-bit, and updating the board core fixes it.

Can I program an Arduino on a Mac without Rosetta?

Only some boards, as of October 2026. Raspberry Pi Pico boards on Earle Philhower's core 6.3.0 and ESP32 boards on Espressif's core 3.3.12 compile and upload with arm64 tools, once you replace Arduino's Intel-only ctags with an arm64 build from arduino/ctags pull request #24. Arduino's own boards, including the Uno, Nano, Uno R4 and MKR family, still need Rosetta for the compiler, the uploader or both.

How this was checked: on 2026-10-21, on a Mac mini (Mac16,10, M4, macOS 26.4.1) that has never had Rosetta installed. I ran lipo, codesign and spctl on the Arduino IDE 2.3.10 arm64 app without launching it. Compiles used arduino-cli 1.5.1, the version the IDE bundles, with arduino:avr 1.8.8, renesas_uno 1.6.0, samd 1.8.14, rp2040:rp2040 6.3.0 and esp32:esp32 3.3.12. The 32-core census reads each core's newest toolsDependencies in the three indexes. No board was connected, so the upload results only show whether the tool starts. ctags was built from arduino/ctags with PR #24, and avr-gcc is Paul Stoffregen's "firsttry" release.