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Flashing Issues

Flashing means copying a .uf2 firmware file onto your keyboard. You put a half into bootloader mode by double-tapping the reset button next to its USB-C port (the switch puller that comes with your Cyboard fits the reset hole), which makes a USB drive named ASSIMILATOR appear. You then drag the .uf2 file onto that drive. The problems below cover what can go wrong.

tip

The full step-by-step for the wireless Imprint lives in the Cyboard Studio Firmware Update guide. This page is just the troubleshooting.

No ASSIMILATOR drive appears​

The drive only shows up when the half is in bootloader mode and connected with a data cable. Check, in order:

  1. Double-tap the reset button — two quick presses, like a mouse double-click. A single press just restarts the keyboard; too slow and it won't enter the bootloader.
  2. Use a data cable, not a charge-only cable. Many USB-C cables carry power but not data. If in doubt, use the cable that came with your Cyboard, or one you know syncs a phone.
  3. Try a different USB port — plug directly into the computer rather than through a hub or dock.
  4. Connect using the port closest to you on the half you're flashing.

An error appears while copying the file​

This is normal — the flash almost certainly worked. When the file finishes copying, the keyboard resets itself immediately, before the operating system gets its final confirmation that the copy is done. So the OS reports an error even though everything went fine. You'll see something like:

  • Windows — "An unexpected error is keeping you from copying the file."
  • macOS — "Error code -36" or "fcopyfile failed: Input/output error."
  • Linux — a failed-to-copy or I/O warning.

Ignore it. To confirm the flash actually worked, just use the keyboard — pair it over Bluetooth, or open Cyboard Studio and connect.

macOS Finder-specific errors​

A couple of older macOS versions had Finder bugs specific to copying .uf2 files:

  • macOS 13.0 (Ventura) could report error code 100093. Fixed in 13.1 — update macOS, or copy the file from the Terminal instead.
  • macOS 14.x (Sonoma) reports error code -36 (see above). This one is harmless and can be ignored; the flash completes.

The drive appears but the file bounces back / won't copy​

Make sure you're copying the correct .uf2 for that half and that the download finished completely. Re-download the firmware and try again. Copying the wrong half's file won't damage anything — the keyboard just won't work right until you flash the correct file, so simply flash again with the right one.

After flashing, the keyboard behaves oddly​

  • Keymap looks different — a fresh firmware ships the standard Cyboard layout. Re-apply your customizations in Cyboard Studio; they're saved on the keyboard from then on.
  • One half is unresponsive, or the halves won't sync — flash both halves with their matching firmware, then follow Reset Your Keyboard's Pairing.

Still stuck? Ask on Discord or email support@cyboard.digital.