bvaughn/react-virtualized · warning

Fixed height CellMeasurerCache should specify a :defaultHeig

Error message

Fixed height CellMeasurerCache should specify a :defaultHeight greater than 0. Failing to do so will lead to unnecessary layout and poor performance.

What it means

When height is NOT fixed (`fixedHeight` is false), CellMeasurerCache uses `defaultHeight` as the estimated height for unmeasured cells. A default of 0 makes the grid render zero-height rows initially, forcing constant relayout/remeasure as cells become visible. Dev-mode console warning only.

Source

Thrown at source/CellMeasurer/CellMeasurerCache.js:84

      this._minHeight,
      typeof defaultHeight === 'number' ? defaultHeight : DEFAULT_HEIGHT,
    );
    this._defaultWidth = Math.max(
      this._minWidth,
      typeof defaultWidth === 'number' ? defaultWidth : DEFAULT_WIDTH,
    );

    if (process.env.NODE_ENV !== 'production') {
      if (this._hasFixedHeight === false && this._hasFixedWidth === false) {
        console.warn(
          "CellMeasurerCache should only measure a cell's width or height. " +
            'You have configured CellMeasurerCache to measure both. ' +
            'This will result in poor performance.',
        );
      }

      if (this._hasFixedHeight === false && this._defaultHeight === 0) {
        console.warn(
          'Fixed height CellMeasurerCache should specify a :defaultHeight greater than 0. ' +
            'Failing to do so will lead to unnecessary layout and poor performance.',
        );
      }

      if (this._hasFixedWidth === false && this._defaultWidth === 0) {
        console.warn(
          'Fixed width CellMeasurerCache should specify a :defaultWidth greater than 0. ' +
            'Failing to do so will lead to unnecessary layout and poor performance.',
        );
      }
    }
  }

  clear(rowIndex: number, columnIndex: number = 0) {
    const key = this._keyMapper(rowIndex, columnIndex);

    delete this._cellHeightCache[key];

View on GitHub (pinned to c737715486)

Solutions

1. Pass an explicit `defaultHeight` greater than 0 (a realistic average row height).
2. Set `fixedHeight: true` if heights are actually constant, providing `defaultHeight` as that constant.
3. Tune `defaultHeight` close to real content height to minimize reflow/jumping.

Example fix

// before
const cache = new CellMeasurerCache({ fixedWidth: true });

// after
const cache = new CellMeasurerCache({ fixedWidth: true, defaultHeight: 64 });

if (!opts.fixedHeight && !(opts.defaultHeight > 0)) throw new Error('Provide defaultHeight > 0 for CellMeasurerCache');

When it happens

Trigger: `new CellMeasurerCache({fixedWidth: true})` (or neither fixed) without supplying `defaultHeight`, since the default is 0.

Common situations: Setting `fixedWidth: true` but forgetting `defaultHeight`; assuming the cache inherits a default height; scrollbars jumping because rows start at 0 height.

Related errors

• Fixed width CellMeasurerCache should specify a :defaultWidth
• CellMeasurerCache should only measure a cell's width or heig
• CellMeasurer registerChild expects to be passed Element or n
• Rendered cell should include style property for positioning.
• Invalid metadata returned for cell ${index}: x:${cel

AI-assisted analysis of bvaughn/react-virtualized@c737715486 (2026-08-30). Data as JSON: /api/errors/a3175436112c0988. Report an issue: GitHub.