Microsoft Edge Officially Drops Default Unload Event Support

Microsoft Edge has officially stopped running unload event handlers by default starting this month. Going forward, websites will need explicit permission to keep using them.

Microsoft Edge’s unload event support is officially gone

The discontinuation of support starts in early September 2026. Microsoft expects it to reach worldwide, GCC, GCC High, and DoD environments by October 2026. The change mainly affects websites and apps that still depend on unload for critical tasks. WebView2 applications and managed Edge environments can also be affected, Microsoft noted in the Admin Center Message ID MC1449170.

Microsoft says unload was never a dependable way to save data or confirm that a session ended. Pages can be suspended or terminated without firing the event. There is another catch. Unload listeners can also stop pages from using the browser’s back/forward cache. That may hurt navigation performance.

Here’s how developerscan prepare now

Microsoft recommends moving data-saving logic to visibilitychange. The transition to a hidden state can provide a more reliable final opportunity to preserve application data. For navigation-related scenarios, Microsoft recommends pagehide. It can respond when users leave a page while remaining compatible with the back/forward cache.

Organizations should identify applications using unload, including third-party libraries. Microsoft also recommends testing critical workflows without the event before the rollout completes. For teams needing more time, Microsoft provides the ForcePermissionPolicyUnloadDefaultEnabled Edge policy. Webites can also explicitly allow unload through Permissions Policy.

These options are temporary migration measures rather than permanent fixes. Microsoft recommends updating affected applications instead of relying on them indefinitely.

via: Neowin