Backstage scaffolder "action ... not found" template failure in CI

The scaffolder runs a template step by looking up a registered action by id. If the action is misspelled or its providing plugin is not installed, the run fails with the action not registered.

What this error means

A scaffolder dry-run or test fails with "Template action with ID 'publish:github' is not registered." naming the missing action id.

backstage

NotFoundError: Template action with ID 'publish:github' is not registered.
    at TemplateActionRegistry.get ...

Common causes

The action plugin is not installed or registered

The action comes from a scaffolder module that is not added to the backend, so its id is unknown.

A typo in the action id

The template step references an id that does not match any registered action.

How to fix it

Install and register the action module

Add the scaffolder backend module that provides the action.
Register it in the backend so its actions load.
Re-run the template.

Terminal

yarn --cwd packages/backend add @backstage/plugin-scaffolder-backend-module-github

Fix the action id in the template

Match the step action to a registered id exactly, checking the actions list the backend exposes.

template.yaml

steps:
  - id: publish
    action: publish:github

How to prevent it

Install the scaffolder modules for every action a template uses.
Dry-run templates in CI so unregistered actions fail early.
Keep action ids in templates matching the registered ids.