mermaid-js/mermaid · error

The group [${id}]'s parent is not a group

Error message

The group [${id}]'s parent is not a group

What it means

Thrown by ArchitectureDB.addGroup when the `in` (parent) field resolves to an id registered as a 'node' (a service or junction) rather than a 'group'. Only groups may contain other groups; services and junctions are leaf nodes and cannot be parents. The registeredIds map distinguishes the two kinds, and this check enforces the type constraint.

Source

Thrown at packages/mermaid/src/diagrams/architecture/architectureDb.ts:176

  }

  public addGroup({ id, icon, in: parent, title }: ArchitectureGroup): void {
    if (this.registeredIds.has(id)) {
      throw new Error(
        `The group id [${id}] is already in use by another ${this.registeredIds.get(id)}`
      );
    }
    if (parent !== undefined) {
      if (id === parent) {
        throw new Error(`The group [${id}] cannot be placed within itself`);
      }
      if (!this.registeredIds.has(parent)) {
        throw new Error(
          `The group [${id}]'s parent does not exist. Please make sure the parent is created before this group`
        );
      }
      if (this.registeredIds.get(parent) === 'node') {
        throw new Error(`The group [${id}]'s parent is not a group`);
      }
    }

    this.registeredIds.set(id, 'group');

    this.groups.set(id, {
      id,
      icon,
      title,
      in: parent,
    });
  }
  public getGroups(): ArchitectureGroup[] {
    return [...this.groups.values()];
  }
  public addEdge({
    lhsId,
    rhsId,

View on GitHub (pinned to d93e9c88c0)

Solutions

1. Point `in` at an id that was registered as a group (via addGroup).
2. If you intended the service to be a container, restructure — services cannot hold groups; promote it to a group instead.

Example fix

// before
db.addService({ id: 'svc1' });
db.addGroup({ id: 'g', in: 'svc1' }); // svc1 is a node, not a group
// after
db.addGroup({ id: 'outer' });
db.addGroup({ id: 'g', in: 'outer' });

function addGroupSafe(db, g) {
  if (g.in !== undefined) {
    const parentIsGroup = db.getGroups().some(gr => gr.id === g.in);
    const parentIsNode = db.getNodes().some(n => n.id === g.in);
    if (parentIsNode && !parentIsGroup) {
      throw new Error(`Parent '${g.in}' is a node, not a group`);
    }
  }
  db.addGroup(g);
}

When it happens

Trigger: Calling db.addGroup({ id: 'g', in: 'svc1' }) where 'svc1' was previously registered via addService or addJunction (registered as 'node').

Common situations: Confusing a service name with a group name when writing containment; typos where a group id collides with a service id; restructuring that moves groups under services.

Related errors

• The group [${id}] cannot be placed within itself
• The group [${id}]'s parent does not exist. Please make sure
• The service [${id}]'s parent is not a group
• The junction [${id}]'s parent is not a group
• The group id [${id}] is already in use by another ${this.reg

AI-assisted analysis of mermaid-js/mermaid@d93e9c88c0 (2026-08-12). Data as JSON: /api/errors/5fde511f211b8a7f. Report an issue: GitHub.