Wt 4.9.1 fixes some regressions that appeared in Wt 4.9.0, mostly related to the JavaScript changes and the Bootstrap 5 theme, and fixes a few other bugs too. See the release notes for more info.
Here are the links:
Wt 4.9.1 (C++): download wt-4.9.1.tar.gz (release notes)
JWt 4.9.1 (Java): download jwt-4.9.1.zip (release notes)
Binary builds for Windows are available on the GitHub releases page.