What causes "mountpoint is already registered: {}" in astrid-runtime/astrid?

Unmount the existing mount at that path before mounting again

mountpoint is already registered: {}

Error message

mountpoint is already registered: {}

What it means

mount() registers a MountRecord in the local registry after the kernel grants a lease. Before inserting, it checks whether the mountpoint is already registered and bails to avoid silently overwriting an existing mount record for the same path.

Source

Thrown at crates/astrid-storage-provider-fskit/src/main.rs:185

    client: &mut AdminClient,
    acting_principal: &astrid_core::PrincipalId,
    view: astrid_core::storage_provider::StorageProviderViewV1,
    access: astrid_core::storage_provider::StorageProviderAccessV1,
    requested_mountpoint: Option<PathBuf>,
) -> Result<StorageProviderSuccessV1> {
    let (mountpoint, auto_created) = prepare_mountpoint(requested_mountpoint, &view)?;
    let body = client
        .request(AdminRequestKind::StorageMountIssue {
            view: view.clone(),
            access,
            provider: PROVIDER_NAME.to_owned(),
            mountpoint: mountpoint.clone(),
        })
        .await?;
    let lease = lease_from_response(body)?;
    if let Err(error) = update_registry(|registry| {
        if registry.mounts.contains_key(&path_key(&mountpoint)) {
            bail!("mountpoint is already registered: {}", mountpoint.display());
        }
        registry.mounts.insert(
            path_key(&mountpoint),
            MountRecord {
                mount_id: lease.mount_id,
                requested_by: acting_principal.clone(),
                mountpoint: mountpoint.clone(),
                access,
                auto_created_mountpoint: auto_created,
            },
        );
        Ok(())
    }) {
        revoke_after_registry_failure(client, lease.mount_id).await;
        return match cleanup_created_mountpoint(&mountpoint, auto_created) {
            Err(cleanup) => Err(error.context(cleanup)),
            Ok(()) => Err(error),
        };

View on GitHub (pinned to affd8760f4)

Solutions

Unmount the existing mount at that path before mounting again
Choose a different mountpoint path
If the record is stale, use the stale-mount cleanup/unmount path to remove it first

Example fix

// before
provider.mount("/mnt/share", ...)?; // second call
// after
if !is_mounted("/mnt/share") {
    provider.mount("/mnt/share", ...)?;
}

Defensive patterns

Strategy: try-catch

Validate before calling

// rust
let key = path_key(&mountpoint);
if registry_has_mount(key) { /* unmount first or pick another path */ }

Try / catch

// rust
match provider.mount(&mountpoint, &opts) {
    Ok(lease) => /* use lease */,
    Err(e) if e.to_string().contains("already registered") => {
        provider.unmount(&mountpoint)?;
        provider.mount(&mountpoint, &opts)
    }
    Err(e) => Err(e),
}

Prevention

Track mounted paths in your tooling and skip already-mounted ones
Always unmount cleanly on shutdown/error paths
Use canonicalized paths so duplicate registrations via symlinks are caught

When it happens

Trigger: Calling execute() with a mount request whose mountpoint path (after path_key normalization) matches an existing entry in registry.mounts.

Common situations: Re-running a mount command for an already-mounted path; case/symlink normalization differences making two textual paths map to the same key; a previous mount that was granted but never cleaned up.

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

AI-assisted analysis of astrid-runtime/astrid@affd8760f4 (2026-09-09). Data as JSON: /api/errors/b0b01ebd0090c764. Report an issue: GitHub.