sharedMemory was requested but the page is not cross-origin isolated; falling back to the copying transport

Warnings reference › worker/shared-unavailable

Identifier

worker/shared-unavailable

Raised by

The grid (background worker)

Since

1.0.1

What happened

SharedArrayBuffer is only constructible on a cross-origin-isolated page, and this page is not one. The shared-handle cache was asked for explicitly and switched itself off, so column handles are copied across the worker boundary instead of shared. Everything still works; large transfers cost a copy each way.

The fix

Serve the page with Cross-Origin-Opener-Policy: same-origin and Cross-Origin-Embedder-Policy: require-corp, which is what makes crossOriginIsolated true - or stop asking for sharedMemory and accept the copying transport.

Reference

Covered in full at the API reference.