This topic describes why template validation fails.


Make sure that the template is a valid JSON or YAML file with UTF-8 encoding. The files are valid if their content can be correctly interpreted as JSON or YAML.

Version (ROSTemplateFormatVersion)

Make sure that ROSTemplateFormatVersion is correctly spelled and the value is 2015-09-01.


Make sure that mapping definitions meet the Resource Orchestration Service (ROS) requirements.

Notice Functions cannot be used in mappings.


Make sure that parameter definitions meet the ROS requirements.

Notice Functions cannot be used in parameters. If the parameter definition contains a constraint and a default value, the default value must also conform to the parameter constraint.


Resource IDs cannot contain forward slashes (/).

A resource definition must contain a Type property whose value is of the String type.

A resource definition can only contain values of the Type, Properties, Metadata, DependsOn, DeletionPolicy, and Description properties.


A value must be defined in an output.

Unsupported resource types

If the template contains unsupported resources, validation fails.


Make sure that the size of the template file is no larger than 512 KB.

Make sure that the template contains only the following top-level objects: ROSTemplateFormatVersion, Description, Mappings, Parameters, Resources, and Outputs.