Identifiers in Planner

Namespace: microsoft.graph

Identifiers for objects in Planner are service-generated string values. The values are 28 characters long and are case-sensitive. When passed as in, the service does a simple format validation of the identifier, if the format validation fails, the callers receive a Bad Request (400) error response indicating this problem. Receiving this error indicates a bug in the calling application, such as:

• The calling application processed the identifier as a case insensitive string. Identifiers in Tasks are case-sensitive.
• The calling application truncated the identifier. Identifiers in Tasks are 28 characters long.
• The calling application attempted to generate an identifier value for an object in Tasks. Client generated identifiers aren't accepted. All identifiers are generated by the service upon the creation of objects.

This validation is not a security feature. It's only meant to inform applications about common identifier related issues during the development of the application, which are otherwise hard to identify.