pulumi/pulumi · error

validating stack config: %w

Error message

validating stack config: %w

What it means

Thrown when pkgWorkspace.ValidateStackConfigAndApplyProjectConfig rejects the stack's config after it was loaded: configuration values violate the schema (wrong types, unknown keys, missing required inputs) or project-level config constraints (allowed values, defaults) can't be applied.

Source

Thrown at pkg/cmd/pulumi/neo/tools/pulumi.go:275

	if err != nil {
		return failedResult(a, "", fmt.Errorf("getting stack: %w", err))
	}
	if s == nil {
		return failedResult(a, "", fmt.Errorf("stack %q not found", a.StackName))
	}

	ssml := cmdStack.NewStackSecretsManagerLoaderFromEnv()
	cfg, sm, err := cmdConfig.GetStackConfiguration(ctx, cmdutil.Diag(), ssml, s, proj, "", nil)
	if err != nil {
		return failedResult(a, "", fmt.Errorf("getting stack configuration: %w", err))
	}

	decrypter := sm.Decrypter()
	encrypter := sm.Encrypter()
	if err := pkgWorkspace.ValidateStackConfigAndApplyProjectConfig(
		ctx, s.Ref().Name().String(), proj, cfg.Environment, cfg.Config, encrypter, decrypter,
	); err != nil {
		return failedResult(a, "", fmt.Errorf("validating stack config: %w", err))
	}

	autonamer, err := autonaming.ParseAutonamingConfig(
		autonamingStackContextFor(proj, s), cfg.Config, decrypter)
	if err != nil {
		return failedResult(a, "", fmt.Errorf("getting autonaming config: %w", err))
	}

	// Pass nil for flags: GetUpdateMetadata only uses them to record
	// "pulumi.flag.<name>" entries, and Neo has no CLI flags to record.
	m, err := metadata.GetUpdateMetadata("" /*message*/, root,
		"neo" /*execKind*/, "" /*execAgent*/, false /*updatePlan*/, cfg, nil)
	if err != nil {
		return failedResult(a, "", fmt.Errorf("gathering metadata: %w", err))
	}

	opts := backend.UpdateOptions{
		AutoApprove: true, // Upstream approval already gates pulumi_up before dispatch.

View on GitHub (pinned to 793f7b2e16)

Solutions

1. Run `pulumi config` / `pulumi up --dry-run` locally to see the exact validation message, then fix the offending key in Pulumi.<stack>.yaml.
2. Add the missing key declaration (with correct type) to the `config:` section of Pulumi.yaml, or delete the undeclared key from stack config.
3. Supply values for required config keys with `pulumi config set <key> <value>` (use --secret as needed).
4. Align value types — quote numbers/bools or use the correct JSON type per the schema.

Example fix

// before (Pulumi.dev.yaml)
config:
  aws:region: 42

// after
config:
  aws:region: us-east-1

// dry-run config validation before the tool call
const { execSync } = require('child_process');
execSync('pulumi preview --expect-no-changes', { stdio: 'pipe', cwd: projDir }); // throws on schema/config violations

try {
  await neo.callTool('pulumi_up', args);
} catch (e) {
  if (/validating stack config:/.test(e.message)) {
    console.error('Fix config per schema:', e.message.replace('validating stack config: ', ''));
  }
}

When it happens

Trigger: Calling pulumi_preview/pulumi_up when a stack config value has the wrong type for its declared type in Pulumi.yaml (e.g. string where a number is required), a config key isn't declared in the project, a required config value is missing, or an environment-injected value conflicts with project constraints.

Common situations: `pulumi config set aws:region us-east-1` typed values that need typed objects; removing a config type declaration from Pulumi.yaml while stack yaml still sets the key; upgrading a provider whose config schema added required fields; environments (Pulumi Cloud) returning values of the wrong shape.

Related errors

• invalid empty stack name
• refusing to remove stack because it still contains resources
• a stack named %s already exists
• writing snapshot: %w
• saving update info: %w

AI-assisted analysis of pulumi/pulumi@793f7b2e16 (2026-08-31). Data as JSON: /api/errors/cba8db77fcddde7d. Report an issue: GitHub.