OK. The created group. New groups are appended to the end of the stored order; if that order row could not be read the group is still created successfully and simply sorts to the end of the list until the next reorder, rather than the existing order being overwritten.

Bad Request. Each cause returns its own message, so the message identifies the fix. The name is rejected when it is missing or not a string, when it is empty once whitespace and invisible format characters are stripped, when it exceeds 250 characters after Unicode NFKC normalisation, or when it stays within 250 characters but exceeds 1024 bytes once casefolded and UTF-8 encoded. Also returned when the organization has reached its 100-group cap.

Forbidden

Conflict. A group with this name (after Unicode normalisation) already exists in the organization. Enforced atomically at the storage layer, so two simultaneous creates of the same name cannot both succeed.

Internal Server Error. The group was not created. Either the existing groups could not be read, so the per-organization cap could not be checked, or the group record itself could not be written.