Touch Board and macOS Catalina

On October 7, Apple released its latest macOS version, macOS Catalina, which brought many great changes but also broke the Touch Board (and every other atmega32u4-based Arduino board). Any user who would upgrade their Mac to Catalina and then try to upload code onto their Touch Board would see the error message “Couldn’t find a Board on the selected port.”. The Touch Board is based on the Arduino Leonardo, and every Leonardo user experienced the same problem at the time. The issue was discussed by fellow Arduino developers in Google Forum, Stack Overflow, Github and so on.

The cause of the error was quickly found: The macOS Catalina update broke the bootloader recognition for atmega32u4-based Arduino boards, including the Touch Board. The bootloader is part of every Arduino board that manages any code uploaded or the code started. A patch for the bootloader was provided by the Arduino developers, but the bootloader cannot be updated with a USB cable. Instead, the bootloader has to be burnt via the ISCP pins, for which we use an AVR ISP programmer. There are other methods that are explained on the Arduino website.

We had the solution, but now we were faced with a tricky situation: how are we going to make sure that our community was still able to use the Touch Board with the latest macOS version? We monitored the queries we got over the following month, simultaneously waiting if Apple was going to reply to the Arduino community. Apple didn’t and we observed that few people actually updated to Catalina and weren’t able to use the Touch Board anymore. To recall all Touch Boards that were already in our warehouse and kits would have been close to impossible. Instead, we decided to update the bootloader and have all future Touch Boards equipped with the latest bootloader.

Just to be clear: any user that is using a Mac with up to macOS Mojave or Windows isn’t affected. Only macOS users with Catalina are experiencing error messages because Apple broke the bootloader recognition. Whilst it’s too late for the majority of the Touch Boards that are already out there, we’re more than happy to help you out if you’ve upgraded to macOS Catalina and are now unable to work with the Touch Board. You can either burn the bootloader yourself or send us your Touch Board and we can do it here in our office. Simply drop us an email at so that we can help you out.