What causes "GenerateProgram is not supported" in pulumi/pulumi?

Test conversion via pkg/codegen/pcl and the real convert pipeline instead of the stub runtime.

GenerateProgram is not supported

Error message

GenerateProgram is not supported

What it means

The deploytest languageRuntime stub does not implement program generation/conversion. GenerateProgram normally converts program sources (e.g. between languages or PCL); the fake runtime always fails. It is a placeholder to satisfy the plugin.LanguageRuntime interface for tests.

Source

Thrown at pkg/resource/deploy/deploytest/languageruntime.go:206

	return nil, nil, nil, errors.New("inline plugins are not currently supported")
}

func (p *languageRuntime) GenerateProject(context.Context, string, string, string,
	bool, string, map[string]string,
) (hcl.Diagnostics, error) {
	return nil, errors.New("GenerateProject is not supported")
}

func (p *languageRuntime) GeneratePackage(context.Context,
	string, string, map[string][]byte, string, map[string]string, bool,
) (hcl.Diagnostics, error) {
	return nil, errors.New("GeneratePackage is not supported")
}

func (p *languageRuntime) GenerateProgram(
	context.Context, map[string]string, string, bool,
) (map[string][]byte, hcl.Diagnostics, error) {
	return nil, nil, errors.New("GenerateProgram is not supported")
}

func (p *languageRuntime) Pack(context.Context, string, string) (string, error) {
	return "", errors.New("Pack is not supported")
}

func (p *languageRuntime) Link(
	context.Context, plugin.ProgramInfo, []workspace.LinkablePackageDescriptor, string,
) (string, error) {
	return "", errors.New("Link is not supported")
}

func (p *languageRuntime) Cancel(context.Context) error {
	p.closed = true

	if p.shutdown != nil {
		p.shutdown()
	}

View on GitHub (pinned to 793f7b2e16)

Solutions

Test conversion via pkg/codegen/pcl and the real convert pipeline instead of the stub runtime.
Use a real language runtime host when testing conversion end-to-end.
Skip program-generation steps in tests that only verify deployment behavior.

Defensive patterns

Strategy: fallback

Try / catch

if _, diags, err := runtime.GenerateProgram(ctx, ...); err != nil && strings.Contains(err.Error(), "GenerateProgram is not supported") {
    // use the convert pipeline / real runtime instead
}

Prevention

Avoid conversion workflows in deploytest tests
Test pcl/convert directly in pkg/codegen

When it happens

Trigger: Calling GenerateProgram on the deploytest runtime, e.g. `pulumi convert`-style tests or any engine flow that asks the language runtime to translate program code.

Common situations: Testing program conversion with the mock runtime; accidental use of deploytest host in conversion codepaths.

Related errors

AI-assisted analysis of pulumi/pulumi@793f7b2e16 (2026-08-31). Data as JSON: /api/errors/a3ccbe42068d522b. Report an issue: GitHub.