mermaid-js/mermaid · error · Error

C4 shape "${fromNode.alias}" has no intersect function. Plea

Error message

C4 shape "${fromNode.alias}" has no intersect function. Please report this to https://github.com/mermaid-js/mermaid/issues

What it means

Thrown by getIntersectPoint when a C4Shape has no `intersect` function. The intersect function is normally assigned to each c4Shape during drawC4ShapeArray pass 2 (c4Shape.intersect = node.intersect). If it is missing when drawRels later tries to compute edge endpoints, this error fires. The message itself directs users to file a bug, signalling this is considered an internal invariant violation rather than a user-input error.

Source

Thrown at packages/mermaid/src/diagrams/c4/c4Renderer.ts:345

  currentBounds.bumpLastMargin(conf.c4ShapeMargin);
};

class Point {
  x: number;
  y: number;

  constructor(x: number, y: number) {
    this.x = x;
    this.y = y;
  }
}

/*
 * Get the intersection of the line between the center point of a rectangle and a point outside the rectangle.
 */
const getIntersectPoint = function (fromNode: C4Shape, endPoint: Point): Point | null {
  if (!fromNode.intersect) {
    throw new Error(
      `C4 shape "${fromNode.alias}" has no intersect function. Please report this to https://github.com/mermaid-js/mermaid/issues`
    );
  }
  const { x, y } = fromNode.intersect(endPoint);
  return new Point(x, y);
};

const getIntersectPoints = function (fromNode: C4Shape, endNode: C4Shape) {
  const endIntersectPoint = { x: 0, y: 0 };
  endIntersectPoint.x = endNode.x + endNode.width / 2;
  endIntersectPoint.y = endNode.y + endNode.height / 2;
  const startPoint = getIntersectPoint(fromNode, endIntersectPoint);

  endIntersectPoint.x = fromNode.x + fromNode.width / 2;
  endIntersectPoint.y = fromNode.y + fromNode.height / 2;
  const endPoint = getIntersectPoint(endNode, endIntersectPoint);
  return { startPoint: startPoint, endPoint: endPoint };
};

View on GitHub (pinned to d93e9c88c0)

Solutions

1. Report the issue to https://github.com/mermaid-js/mermaid/issues as the message instructs, including the diagram that triggers it.
2. Simplify the C4 diagram (fewer/custom shape variants) to isolate which shape lacks the intersect function.
3. Upgrade mermaid — the missing intersect assignment may be fixed in a newer release.

try {
  await mermaid.render(id, c4DiagramText);
} catch (err) {
  if (err instanceof Error && err.message.includes('has no intersect function')) {
    // Internal invariant violation — report upstream and simplify the diagram.
  }
  throw err;
}

When it happens

Trigger: Calling drawRels on a C4Shape whose intersect was never set — e.g. because drawC4ShapeArray was skipped, errored mid-pass for that shape, or the underlying unified shape did not provide an intersect function.

Common situations: Internal bug where a shape handler in the registry does not attach an intersect function; partial render after an earlier shape threw; shape handler mismatch across versions.

Related errors

• C4: no shape handler for "${node.shape}"
• C4 rel "${rel.from}" -> "${rel.to}" references an unknown sh
• Could not calculate intersection points for rel "${rel.from}
• Layout data is required

AI-assisted analysis of mermaid-js/mermaid@d93e9c88c0 (2026-08-12). Data as JSON: /api/errors/ee5fee0dd62b83ed. Report an issue: GitHub.