Issue
Google and Microsoft are jointly retiring the legacy unload event in Chromium-based browsers. Chrome began a staged, percentage-based rollout in March 2025 and reaches 100% of all Chrome page loads on Chrome 154 (September 22, 2026). For details see Deprecating the unload event.
Microsoft Edge (also Chromium-based) is retiring default unload support on the same general timeframe, beginning September 2026. For details see Force Permission Policy Unload Default Enabled.
Symptoms and Impact
While Pega has not identified any direct end-user impact at this time, applications that rely on the unload event may experience behavior changes when users navigate away from or close a page. Currently, these changes are limited to browser console violation errors and have no known functional impact. Some Dev Studio users have reported issues when launching or closing the Tracer tool window. In these cases, the following browser console message may appear: "[Violation] Permissions policy violation: unload is not allowed in this document."
If additional symptoms are identified, this document will be updated.
Solution
Pega is working on fixes for currently supported Pega Platform releases. Information about the available fixes will be published as soon as it is available. If you need assistance in the meantime, create a support request with Global Client Support in My Support Portal.
Additional guidance:
- To control access to the unload event, refer to the Chromium guidance here: Control access to unload.
- If your custom code uses unload events, refer to the Chromium guidance for recommended alternatives: Alternatives to unload events.
- Based on currently available information, this unload event deprecation applies only to Chromium-based browsers.