mermaid-js/mermaid · error · Error

The index ${pos} for linkStyle is out of bounds. Valid indic

Error message

The index ${pos} for linkStyle is out of bounds. Valid indices for linkStyle are between 0 and ${this.edges.length - 1}. (Help: Ensure that the index is within the range of existing edges.)

What it means

Error "The index ${pos} for linkStyle is out of bounds. Valid indices for linkStyle are between 0 and ${this.edges.length - 1}. (Help: Ensure that the index is within the range of existing edges.)" thrown in mermaid-js/mermaid.

Source

Thrown at packages/mermaid/src/diagrams/flowchart/flowDb.ts:394

   */
  public updateLinkInterpolate(positions: ('default' | number)[], interpolate: string) {
    positions.forEach((pos) => {
      if (pos === 'default') {
        this.edges.defaultInterpolate = interpolate;
      } else {
        this.edges[pos].interpolate = interpolate;
      }
    });
  }

  /**
   * Updates a link with a style
   *
   */
  public updateLink(positions: ('default' | number)[], style: string[]) {
    positions.forEach((pos) => {
      if (typeof pos === 'number' && pos >= this.edges.length) {
        throw new Error(
          `The index ${pos} for linkStyle is out of bounds. Valid indices for linkStyle are between 0 and ${
            this.edges.length - 1
          }. (Help: Ensure that the index is within the range of existing edges.)`
        );
      }
      if (pos === 'default') {
        this.edges.defaultStyle = style;
      } else {
        this.edges[pos].style = style;
        // if edges[pos].style does have fill not set, set it to none
        if (
          (this.edges[pos]?.style?.length ?? 0) > 0 &&
          !this.edges[pos]?.style?.some((s) => s?.startsWith('fill'))
        ) {
          this.edges[pos]?.style?.push('fill:none');
        }
      }
    });

View on GitHub (pinned to d93e9c88c0)

When it happens

Trigger: Thrown at packages/mermaid/src/diagrams/flowchart/flowDb.ts:394 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of mermaid-js/mermaid@d93e9c88c0 (2026-08-12). Data as JSON: /api/errors/856cd2be07127146. Report an issue: GitHub.