astrid-runtime/astrid · error

WinFsp directory mountpoint must not already exist: {}

Error message

WinFsp directory mountpoint must not already exist: {}

What it means

WinFsp creates and owns the directory mountpoint leaf itself; the provider therefore requires that the final leaf path does NOT already exist. `prepare_mountpoint` checks `symlink_metadata` on the mountpoint and bails if anything (file, directory, or symlink) is present, so cleanup on failure/unmount stays idempotent and WinFsp can create the leaf cleanly.

Source

Thrown at crates/astrid-storage-provider-winfsp/src/main.rs:372

    }

    let parent = mountpoint
        .parent()
        .context("WinFsp directory mountpoint has no parent")?;
    std::fs::create_dir_all(parent)
        .with_context(|| format!("create mountpoint parent {}", parent.display()))?;
    astrid_core::platform_fs::verify_no_redirects(parent)
        .with_context(|| format!("reject redirected mountpoint parent {}", parent.display()))?;
    if !std::fs::symlink_metadata(parent)?.is_dir() {
        bail!("mountpoint parent is not a directory: {}", parent.display());
    }
    match std::fs::symlink_metadata(&mountpoint) {
        Err(error) if error.kind() == std::io::ErrorKind::NotFound => {},
        Err(error) => {
            return Err(error)
                .with_context(|| format!("inspect mountpoint {}", mountpoint.display()));
        },
        Ok(_) => bail!(
            "WinFsp directory mountpoint must not already exist: {}",
            mountpoint.display()
        ),
    }
    // WinFsp creates and owns directory mountpoint leaves. Treat the leaf as
    // provider-created so failure and unmount cleanup remain idempotent.
    Ok((mountpoint, true))
}

#[cfg(not(windows))]
fn prepare_mountpoint(
    _requested: Option<PathBuf>,
    _view: &astrid_core::storage_provider::StorageProviderViewV1,
) -> Result<(PathBuf, bool)> {
    bail!("the WinFsp provider is available only on Windows")
}

#[cfg(windows)]

View on GitHub (pinned to affd8760f4)

Solutions

1. Delete the existing empty directory at the mountpoint path, then retry the mount
2. Choose a different mountpoint leaf path
3. If the leftover is a live mount, unmount it properly first via the provider's `unmount`

Example fix

// before
std::fs::create_dir_all("C:\\mounts\\storage")?; // pre-creating the leaf breaks WinFsp
mount(provider, Some(PathBuf::from("C:\\mounts\\storage"))).await?;
// after: let WinFsp create the leaf
mount(provider, Some(PathBuf::from("C:\\mounts\\storage"))).await?;

// Ensure the mountpoint leaf does not exist before mounting
fn leaf_free(mountpoint: &std::path::Path) -> bool {
    matches!(std::fs::symlink_metadata(mountpoint), Err(e) if e.kind() == std::io::ErrorKind::NotFound)
}

When it happens

Trigger: Calling `mount` with a directory mountpoint path where the leaf already exists — e.g. a previous mount crashed without cleanup, the user pre-created the folder, or a stale empty directory was left behind.

Common situations: Re-mounting after an unclean shutdown or provider crash that left the empty leaf directory; scripts that `mkdir` the mountpoint first out of habit from other FUSE-like tools; leftover directories from an uninstalled setup.

Understand the failure class

Background: "already exists" / EEXIST / FileAlreadyExistsException: what the 'file already exists' error means and how to fix it — this error's family across 37 libraries.

Related errors

• mountpoint must be absolute
• mountpoint parent is not a directory: {}
• no free Windows drive target is available; specify a directo
• WinFsp failed to start private mount: {status:#x}
• mountpoint is already registered: {}

AI-assisted analysis of astrid-runtime/astrid@affd8760f4 (2026-09-09). Data as JSON: /api/errors/342c9e29b0e69a2a. Report an issue: GitHub.