zeroclaw-labs/zeroclaw · error

UF2 at {} does not look like a valid UF2 file (magic mismatc

Error message

UF2 at {} does not look like a valid UF2 file (magic mismatch). Download from https://micropython.org/download/RPI_PICO/ and delete the existing file so ZeroClaw can re-extract it.

What it means

Error "UF2 at {} does not look like a valid UF2 file (magic mismatch). Download from https://micropython.org/download/RPI_PICO/ and delete the existing file so ZeroClaw can re-extract it." thrown in zeroclaw-labs/zeroclaw.

Source

Thrown at crates/zeroclaw-hardware/src/uf2.rs:103

// ── Flashing ──────────────────────────────────────────────────────────────────

pub async fn flash_uf2(mount_point: &Path, firmware_dir: &Path) -> Result<()> {
    let uf2_src = firmware_dir.join("zeroclaw-pico.uf2");
    let uf2_dst = mount_point.join("firmware.uf2");
    let src_str = uf2_src.to_string_lossy().into_owned();
    let dst_str = uf2_dst.to_string_lossy().into_owned();

    ::zeroclaw_log::record!(
        INFO,
        ::zeroclaw_log::Event::new(module_path!(), ::zeroclaw_log::Action::Note)
            .with_attrs(::serde_json::json!({"src": src_str, "dst": dst_str})),
        "flashing UF2"
    );

    // Validate UF2 magic before any copy attempt — prevents flashing a stub.
    let data = std::fs::read(&uf2_src)?;
    if data.len() < 8 || data[..4] != UF2_MAGIC1 {
        bail!(
            "UF2 at {} does not look like a valid UF2 file (magic mismatch). \
             Download from https://micropython.org/download/RPI_PICO/ and delete \
             the existing file so ZeroClaw can re-extract it.",
            uf2_src.display()
        );
    }

    // ── Attempt 1: std::fs::copy (works on Linux, sometimes blocked on macOS) ─
    {
        let src = uf2_src.clone();
        let dst = uf2_dst.clone();
        let result = tokio::task::spawn_blocking(move || std::fs::copy(&src, &dst))
            .await
            .map_err(|e| {
                ::zeroclaw_log::record!(
                    ERROR,
                    ::zeroclaw_log::Event::new(module_path!(), ::zeroclaw_log::Action::Fail)
                        .with_outcome(::zeroclaw_log::EventOutcome::Failure)

View on GitHub (pinned to 88bb9c8533)

Solutions

1. Download a valid UF2 from https://micropython.org/download/RPI_PICO/ and delete the existing corrupt file so ZeroClaw can re-extract it.

When it happens

Trigger: Thrown at crates/zeroclaw-hardware/src/uf2.rs:103 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of zeroclaw-labs/zeroclaw@88bb9c8533 (2026-08-23). Data as JSON: /api/errors/3fa4848a30ce67f9. Report an issue: GitHub.