grafana/k6 · error

restoring viewport to

Error message

restoring viewport to %s: %w

What it means

Raised at the end of screenshotPage when a full-page screenshot required enlarging the viewport (overriddenViewportSize != nil) and restoring the original viewport via restoreViewport fails. The '%s' is the original viewport size being restored. This is a cleanup-path failure: the screenshot bytes were already captured but the CDP call to reset the device metrics override was rejected, commonly because the page or CDP session closed mid-operation, so the error replaces the successful result.

Solutions

1. Keep the page and browser alive until the screenshot call fully completes
2. Retry the screenshot on a healthy page/session
3. Avoid extremely large full-page captures that stress the target during viewport restore
4. Check the wrapped CDP error for the precise override-reset failure

When it happens

Trigger: Thrown at internal/js/modules/k6/browser/common/screenshotter.go:410 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of grafana/k6@3fcf5388d7 (2026-09-20). Data as JSON: /api/errors/358db0b40c110b6f. Report an issue: GitHub.

Appendix: source

Thrown at internal/js/modules/k6/browser/common/screenshotter.go:400

	}
	originalSize := p.emulatedSize

	if opts.FullPage { //nolint:nestif
		fullPageSize, sizeErr := s.fullPageSize(p)
		if sizeErr != nil {
			return nil, fmt.Errorf("getting full page size: %w", sizeErr)
		}
		documentRect := &Rect{
			X:      0,
			Y:      0,
			Width:  fullPageSize.Width,
			Height: fullPageSize.Height,
		}
		fitsViewport := fullPageSize.Width <= viewportSize.Width && fullPageSize.Height <= viewportSize.Height
		if !fitsViewport {
			defer func() {
				if restoreErr := s.restoreViewport(p, originalSize); restoreErr != nil {
					err = errors.Join(err, fmt.Errorf("restoring viewport to %s: %w",
						viewportSize, restoreErr))
				}
			}()
			if err := p.setViewportSize(s.ctx, fullPageSize); err != nil {
				return nil, fmt.Errorf("setting viewport size to %s: %w",
					fullPageSize, err)
			}
		}
		if opts.Clip != nil {
			documentRect, err = s.trimClipToSize(&Rect{
				X:      opts.Clip.X,
				Y:      opts.Clip.Y,
				Width:  opts.Clip.Width,
				Height: opts.Clip.Height,
			}, &Size{Width: documentRect.Width, Height: documentRect.Height})
			if err != nil {
				return nil, fmt.Errorf("trimming clip to size: %w", err)
			}

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