lima-vm/lima · warning

unimplemented

Error message

unimplemented

What it means

The WSL2 driver does not implement snapshot or display-connection operations. Callers of CreateSnapshot, ApplySnapshot, DeleteSnapshot, ListSnapshots, ChangeDisplayPassword, or DisplayConnection receive this sentinel error (errUnimplemented) unconditionally — the feature simply does not exist on the WSL2 backend.

Source

Thrown at pkg/driver/wsl2/errors_windows.go:10

//go:build windows && !no_wsl

// SPDX-FileCopyrightText: Copyright The Lima Authors
// SPDX-License-Identifier: Apache-2.0

package wsl2

import "errors"

var errUnimplemented = errors.New("unimplemented")

View on GitHub (pinned to dd909d0973)

Solutions

1. Check driver type before calling: only the QEMU/VZ backends support these operations
2. Use WSL-native alternatives (export/import the distro: `wsl.exe --export/--import`) for snapshot-like backups
3. Skip display-password calls on WSL2 — there is no VNC-style display; use `wsl.exe` direct shell access
4. Guard feature probes by treating this error as 'not supported' rather than retrying

Example fix

// before
err := driver.CreateSnapshot(ctx, "snap1") // "unimplemented"
// after
if driverName == "wsl2" {
    return errors.New("snapshots unsupported on wsl2; use wsl --export instead")
}
err := driver.CreateSnapshot(ctx, "snap1")

var snapshotCapable = map[string]bool{"qemu": true, "vz": true}
func canSnapshot(driverName string) bool { return snapshotCapable[driverName] }

func supportsSnapshots(driver driver.Driver) bool {
    type snapper interface { CreateSnapshot(context.Context, string) error }
    _, ok := driver.(snapper)
    return ok
}

if err := driver.CreateSnapshot(ctx, name); err != nil {
    if errors.Is(err, errUnimplemented) || err.Error() == "unimplemented" {
        return fallbackExportDistro(ctx) // wsl --export based backup
    }
    return err
}

When it happens

Trigger: Calling any of the snapshot-related driver methods (CreateSnapshot, ApplySnapshot, DeleteSnapshot, ListSnapshots) or display methods (ChangeDisplayPassword, DisplayConnection) on an instance driven by the wsl2 driver on Windows.

Common situations: Scripts or tools written against the QEMU driver ported to Windows/WSL2; automation that snapshots VMs before changes; UI/tooling probing capabilities without checking the driver type first.

Related errors

• unimplemented
• cannot use `--sync` with a wsl2 instance, the host directory
• unimplemented by the krunkit driver
• failed to run `wsl.exe --distribution %s`: %w (out=%#q)
• failed to run `wsl.exe --import %s %s %s`: %w (out=%#q)

AI-assisted analysis of lima-vm/lima@dd909d0973 (2026-09-01). Data as JSON: /api/errors/597bae63ae78a374. Report an issue: GitHub.