Found the following validation problem for the NEWS.Rd HTML conversion:
NEWS.html:1453:1 (inst/NEWS.Rd:679): Warning: missing </ul> before </div>
NEWS.html:327:1 (inst/NEWS.Rd:161): Warning: <h4> anchor "bugfixes-and-minor-changes" already defined
NEWS.html:375:1 (inst/NEWS.Rd:191): Warning: <h4> anchor "New-features" already defined
NEWS.html:414:1 (inst/NEWS.Rd:206): Warning: <h4> anchor "bugfixes-and-minor-changes" already defined
NEWS.html:447:1 (inst/NEWS.Rd:223): Warning: <h4> anchor "bugfixes-and-minor-changes" already defined
NEWS.html:462:1 (inst/NEWS.Rd:232): Warning: <h4> anchor "New-features" already defined
NEWS.html:495:1 (inst/NEWS.Rd:249): Warning: <h4> anchor "bugfixes-and-minor-changes" already defined
NEWS.html:587:1 (inst/NEWS.Rd:288): Warning: <h4> anchor "bugfixes-and-minor-changes" already defined
NEWS.html:605:1 (inst/NEWS.Rd:299): Warning: <h4> anchor "New-features" already defined
NEWS.html:619:1 (inst/NEWS.Rd:306): Warning: <h4> anchor "bugfixes-and-minor-changes" already defined
NEWS.html:671:1 (inst/NEWS.Rd:327): Warning: <h4> anchor "New-features" already defined
NEWS.html:731:1 (inst/NEWS.Rd:354): Warning: <h4> anchor "bugfixes-and-minor-changes" already defined
NEWS.html:764:1 (inst/NEWS.Rd:369): Warning: <h4> anchor "New-features" already defined
NEWS.html:801:1 (inst/NEWS.Rd:386): Warning: <h4> anchor "bugfixes-and-minor-changes" already defined
NEWS.html:834:1 (inst/NEWS.Rd:400): Warning: <h4> anchor "New-features" already defined
NEWS.html:873:1 (inst/NEWS.Rd:419): Warning: <h4> anchor "bugfixes-and-minor-changes" already defined
NEWS.html:1120:1 (inst/NEWS.Rd:541): Warning: <h4> anchor "R-code" already defined
NEWS.html:1234:1 (inst/NEWS.Rd:589): Warning: <h4> anchor "Package-documentation" already defined
NEWS.html:1272:1 (inst/NEWS.Rd:603): Warning: <h4> anchor "Misc" already defined
NEWS.html:1301:1 (inst/NEWS.Rd:618): Warning: <h4> anchor "R-code" already defined
NEWS.html:1321:1 (inst/NEWS.Rd:626): Warning: <h4> anchor "Package-documentation" already defined
NEWS.html:1338:1 (inst/NEWS.Rd:633): Warning: <h4> anchor "Misc" already defined
NEWS.html:1365:1 (inst/NEWS.Rd:647): Warning: <h4> anchor "R-code" already defined
NEWS.html:1418:1 (inst/NEWS.Rd:666): Warning: <h4> anchor "Package-documentation" already defined
NEWS.html:1436:1 (inst/NEWS.Rd:674): Warning: <h4> anchor "Misc" already defined