lima-vm/lima · critical

failed to validate the instance YAML after filling defaults:

Error message

failed to validate the instance YAML after filling defaults: %w

What it means

After creating the driver, HostAgent.New re-runs limayaml.Validate on the instance config with warnings enabled, verifying the YAML is still valid once defaults are filled in. Failure means the defaulted config violates the Lima schema or semantic constraints; the error is wrapped with this message.

Source

Thrown at pkg/hostagent/hostagent.go:174

	var udpDNSLocalPort, tcpDNSLocalPort int
	if limayaml.HostResolverEnabled(inst.Config) {
		udpDNSLocalPort, err = freeport.UDP()
		if err != nil {
			return nil, err
		}
		tcpDNSLocalPort, err = freeport.TCP()
		if err != nil {
			return nil, err
		}
	}

	limaDriver, err := driverutil.CreateConfiguredDriver(ctx, inst, sshLocalPort)
	if err != nil {
		return nil, fmt.Errorf("failed to create driver instance: %w", err)
	}
	if err := limayaml.Validate(inst.Config, true); err != nil {
		return nil, fmt.Errorf("failed to validate the instance YAML after filling defaults: %w", err)
	}
	sshLocalPort = inst.SSHLocalPort

	info := limaDriver.Info(ctx)
	vSockPort := info.VsockPort
	virtioPort := info.VirtioPort
	noCloudInit := info.Features.NoCloudInit
	rosettaEnabled := info.Features.RosettaEnabled
	rosettaBinFmt := info.Features.RosettaBinFmt

	// Disable Rosetta in Plain mode
	if *inst.Config.Plain {
		rosettaEnabled = false
		rosettaBinFmt = false
	}

	var iid string
	switch *inst.Config.OS {

View on GitHub (pinned to dd909d0973)

Solutions

1. Read the wrapped limayaml validation error — it names the exact offending field and constraint
2. Fix the invalid field in ~/.lima/<instance>/lima.yaml (or the source template and re-provision)
3. Run 'limactl validate <file>' on your YAML before starting to catch issues early
4. Ensure the limactl binary version matches the Lima version that created the instance

Example fix

// before (lima.yaml)
cpus: "four"
// after
cpus: 4

// pre-validate the config before starting the instance
yamlBytes, _ := os.ReadFile("~/.lima/default/lima.yaml")
y, err := limayaml.Load(yamlBytes, "<file>")
if err != nil { return err }
if err := limayaml.Validate(limayaml.FillDefaults(y), true); err != nil {
	return fmt.Errorf("config invalid before start: %w", err)
}

err := limayaml.Validate(inst.Config, true)
if err != nil {
	// surface field-level errors to the user instead of a generic start failure
	return fmt.Errorf("fix lima.yaml: %w", err)
}

When it happens

Trigger: limactl start (via hostagentAction → hostagent.New) on an instance whose lima.yaml — after ApplyDefaults — fails validation: invalid enum values, contradictory fields, out-of-range numbers, or invalid combinations of plain/mount/disk settings.

Common situations: Hand-edited lima.yaml introducing an invalid value; config produced by a newer Lima version then loaded by an older limactl; template merge producing conflicting fields; typos in field names that default wrongly.

Understand the failure class

Background: Schema validation failed / invalid input schema: payload rejected because its shape doesn't match the expected schema — this error's family across 28 libraries.

Related errors

• the YAML is invalid, saved the buffer as %#q: %w
• failed to validate YAML file %#q: %w
• failed to validate the instance YAML after filling defaults:
• failed to validate the instance YAML after filling defaults:
• the YAML is invalid, attempted to save the buffer as %#q but

AI-assisted analysis of lima-vm/lima@dd909d0973 (2026-09-01). Data as JSON: /api/errors/1e7a5aa767d37367. Report an issue: GitHub.