Preact 11.0.0 Stable Drops IE11 and Removes SuspenseList, Followed by 11.0.1 Fixes

Overview

The Preact project published version 11.0.0 on September 30, 2026, and followed it with 11.0.1 on October 8. The stable release notes are short: they link six earlier prerelease notes (11.0.0-beta.0 through 11.0.0-rc.2) and then list a handful of final fixes. The breaking changes and new features for the major version are recorded in those earlier prerelease pages.

What We Know

Breaking changes from the first beta

The 11.0.0-beta.0 release notes have a “Breaking Changes” section that includes:

• “Drop IE11 support”
• “Move defaultProps into preact/compat”
• “Remove automatic px suffix”
• “Remove component.base”
• “Remove SuspenseList”
• “Drop support for TS versions < 5.1”

The same page lists “Require initial value in useRef” under its Types heading and “Switch to Object.is for hook args” under Refactors. Its Features section includes “Comment denoted hydration”, “Forward ref by default” and “Add captureOwnerStack”.

Features added during the prerelease cycle

The 11.0.0-beta.2 notes list “Implement streamed hydration rfc” under Features. The 11.0.0-rc.0 notes add three more Features entries: “implement use in compat”, “Support createPortal in core” and “Add useEffectEvent hook to compat”. That release candidate also lists “Leverage moveBefore rather than insertBefore when available” under Correctness, “Compute minimal child moves with a longest increasing subsequence” under Performance, and “Bump reported React version to 19.0.0” under Maintenance.

What 11.0.0 itself changed

The 11.0.0 release notes contain nine fixes, one performance entry and four maintenance entries. Among the fixes are “Re-attach refs when a suspended subtree reveals”, “Stop DOM nesting validation at portal boundaries” and “Preserve the casing of camelCase custom event names”. The performance entry is “Remove cloneNode for top-level Fragments”.

The 11.0.1 follow-up

The 11.0.1 release notes list three fixes: “Keep suspended hydration within a component’s own $s range”, “Keep ref cleanups on the element instead of the ref function” and “Unmount parked Suspense children when the boundary unmounts”. They also add a DX entry, “Log the component stack of errors no boundary handles”, and a performance entry, “Key event listeners by prop name and stamp attach times per listener”.

What We Don’t Know

• The release notes cited here do not give migration effort, bundle-size figures or benchmark results for the major version, so none are reported.
• The release pages do not say how many projects are affected by the removal of IE11 support or SuspenseList.
• The notes do not state why the patch release followed the stable release eight days later.

Analysis

The 11.0.1 fixes center on Suspense, hydration and ref cleanup, areas the 11.0.0 notes also touch with their fix “Re-attach refs when a suspended subtree reveals”. Teams upgrading from Preact 10 can read the breaking-change list in the beta.0 notes as the most compact record of what was removed or moved, such as defaultProps and component.base.