Service configuration validation

The framework validates service configuration with the help of AJV (JSON-schema validation engine).

If you were presented with configuration error (or a warning, depending on configValidationMode setting) it could mean that:

  • Service configuration is invalid and you need to correct an issue related to your serverless.yml
  • Configuration related to external plugin does not have an associated JSON Schema. In such cases, please report the issue with the plugin author and provide them the details on how to extend validation schema in order to permanently correct the issue.
  • However unlikely, there may be a bug (or missing) schema configuration for the framework. If you believe this to be the case please report at

Note: In a warning mode (with configValidationMode: warn set in configuration) Framework commands are not blocked in any way, e.g. sls deploy will still attempt to deploy the service normally (still depending on the source of the warning, success of a deployment may vary)

When the setting is not explicitly specified, serverless defaults to configValidationMode: warn. If you find this functionality problematic, you may also turn it off with configValidationMode: off setting.


Add configValidationMode to your service configuration with one of the following values:

Value Effect
error Fail invoked command and output configuration errors.
warn Output configuration errors in form of warnings.
off Suppress configuration errors.
Go to Github