Self update is not supported on Windows. Use install instruc

Error message

Self update is not supported on Windows. Use install instructions on the Wasmer homepage: https://wasmer.io

What it means

The `wasmer self-update` command refuses to run on Windows. Self-updating via binary replacement is only implemented for Unix-like targets, so the Windows-specific `inner_execute` unconditionally aborts with `anyhow::bail!` and points users to the official install instructions at https://wasmer.io. It is a deliberate platform limitation, not a runtime failure.

Source

Thrown at lib/cli/src/commands/self_update.rs:35

        println!("Fetching latest installer");
        let cmd = Command::new("curl")
            .arg("https://get.wasmer.io")
            .arg("-sSfL")
            .stdout(Stdio::piped())
            .spawn()?;

        let mut process = Command::new("sh")
            .stdin(cmd.stdout.unwrap())
            .stdout(Stdio::inherit())
            .spawn()?;

        process.wait().unwrap();
        Ok(())
    }

    #[cfg(target_os = "windows")]
    fn inner_execute(&self) -> Result<(), anyhow::Error> {
        anyhow::bail!(
            "Self update is not supported on Windows. Use install instructions on the Wasmer homepage: https://wasmer.io"
        );
    }
}

View on GitHub (pinned to 8c4b9ee9d3)

Solutions

Upgrade via the Windows installer from https://wasmer.io instead of `wasmer self-update`
Use the package manager that installed it (e.g. `winget upgrade Wasmer.Wasmer` or `scoop update wasmer`)
Guard automation scripts: only call `wasmer self-update` when cfg!(target_os = "windows") is false

Example fix

// before (CI script)
wasmer self-update || exit 1
// after (shell)
if ! uname -s | grep -qi mingw; then wasmer self-update; fi

Defensive patterns

Strategy: validation

Validate before calling

if cfg!(target_os = "windows") {
    eprintln!("self-update unsupported on Windows; install from https://wasmer.io");
    return;
}
wasmer_cli::commands::self_update::SelfUpdate::new().execute()?;

Type guard

fn can_self_update() -> bool {
    !cfg!(target_os = "windows")
}

Prevention

Branch upgrade logic on OS before invoking self-update
On Windows use winget/scoop or the installer for upgrades
Pin CLI versions in CI and update them via package management, not self-update

When it happens

Trigger: Running `wasmer self-update` (SelfUpdate::execute -> inner_execute) on any Windows build of the CLI. The #[cfg(target_os = "windows")] variant always bails; no other condition matters.

Common situations: Windows users installing Wasmer via scoop/winget/installer and later trying to upgrade in place with the CLI; CI scripts written for Linux/macOS that unconditionally run `wasmer self-update`.

Understand the failure class

Background: "unsupported platform" / "not supported on this platform" errors: what they mean and how to fix them — this error's family across 47 libraries.

Related errors

AI-assisted analysis of wasmerio/wasmer@8c4b9ee9d3 (2026-09-01). Data as JSON: /api/errors/7f1838041f84e1e0. Report an issue: GitHub.