Supported preservation-safe reuse of a 152.0.4191.66 user data folder with Fixed Runtime 152.0.4191.62 x64

We are preparing an isolated Windows x64 desktop application that must preserve an existing WebView2 user data folder and its persistent application state.

The user data folder's recorded Last Version is 152.0.4191.66. The newest Fixed Version x64 CAB offered on the official WebView2 download page at 2026-09-08 16:28 UTC was 152.0.4191.62. We have not opened the preserved profile with the older runtime, so we are not claiming an observed incompatibility.

Can Microsoft confirm whether this exact .66-to-.62 transition is supported without resetting the user data folder or losing persistent storage, cookies, settings, or other profile state? We need profile/storage compatibility guidance, separately from SDK/API compatibility or runtime-selection policy.

If this transition is not supported, is there an official Fixed Version x64 package at 152.0.4191.66 or newer, or a documented preservation-safe migration route?

No profile files, logs, account details, local paths, or private application data are attached.

No repository files, tests, or code entry points are mentioned. Start by checking official WebView2 Fixed Version runtime and user-data-folder compatibility guidance for the stated .66-to-.62 transition; done means a maintainer provides an authoritative compatibility answer or identifies a supported runtime or migration path.