Found the following validation problem for the NEWS.Rd HTML conversion:
NEWS.html:2462:1 (inst/NEWS.Rd:1403): Warning: missing </ul> before </div>
NEWS.html:61:1 (inst/NEWS.Rd:29): Warning: <h4> anchor "NEW-FEATURES" already defined
NEWS.html:80:1 (inst/NEWS.Rd:40): Warning: <h4> anchor "USER-VISIBLE-CHANGES" already defined
NEWS.html:108:1 (inst/NEWS.Rd:56): Warning: <h4> anchor "USER-VISIBLE-CHANGES" already defined
NEWS.html:139:1 (inst/NEWS.Rd:72): Warning: <h4> anchor "BUG-FIXES" already defined
NEWS.html:167:1 (inst/NEWS.Rd:87): Warning: <h4> anchor "BUG-FIXES" already defined
NEWS.html:191:1 (inst/NEWS.Rd:101): Warning: <h4> anchor "BUG-FIXES" already defined
NEWS.html:203:1 (inst/NEWS.Rd:107): Warning: <h4> anchor "USER-VISIBLE-CHANGES" already defined
NEWS.html:220:1 (inst/NEWS.Rd:117): Warning: <h4> anchor "USER-VISIBLE-CHANGES" already defined
NEWS.html:236:1 (inst/NEWS.Rd:126): Warning: <h4> anchor "NEW-FEATURES" already defined
NEWS.html:249:1 (inst/NEWS.Rd:133): Warning: <h4> anchor "USER-VISIBLE-CHANGES" already defined
NEWS.html:266:1 (inst/NEWS.Rd:143): Warning: <h4> anchor "BUG-FIXES" already defined
NEWS.html:280:1 (inst/NEWS.Rd:151): Warning: <h4> anchor "NEW-FEATURES" already defined
NEWS.html:295:1 (inst/NEWS.Rd:159): Warning: <h4> anchor "BUG-FIXES" already defined
NEWS.html:317:1 (inst/NEWS.Rd:175): Warning: <h4> anchor "NEW-FEATURES" already defined
NEWS.html:341:1 (inst/NEWS.Rd:188): Warning: <h4> anchor "USER-VISIBLE-CHANGES" already defined
NEWS.html:362:1 (inst/NEWS.Rd:201): Warning: <h4> anchor "BUG-FIXES" already defined
NEWS.html:378:1 (inst/NEWS.Rd:210): Warning: <h4> anchor "BUG-FIXES" already defined
NEWS.html:399:1 (inst/NEWS.Rd:222): Warning: <h4> anchor "USER-VISIBLE-CHANGES" already defined
NEWS.html:421:1 (inst/NEWS.Rd:234): Warning: <h4> anchor "BUG-FIXES" already defined
NEWS.html:447:1 (inst/NEWS.Rd:249): Warning: <h4> anchor "USER-VISIBLE-CHANGES" already defined
NEWS.html:459:1 (inst/NEWS.Rd:255): Warning: <h4> anchor "BUG-FIXES" already defined
NEWS.html:495:1 (inst/NEWS.Rd:274): Warning: <h4> anchor "USER-VISIBLE-CHANGES" already defined
NEWS.html:532:1 (inst/NEWS.Rd:293): Warning: <h4> anchor "BUG-FIXES" already defined
NEWS.html:555:1 (inst/NEWS.Rd:305): Warning: <h4> anchor "USER-VISIBLE-CHANGES" already defined
NEWS.html:569:1 (inst/NEWS.Rd:311): Warning: <h4> anchor "BUG-FIXES" already defined
NEWS.html:594:1 (inst/NEWS.Rd:325): Warning: <h4> anchor "USER-VISIBLE-CHANGES" already defined
NEWS.html:623:1 (inst/NEWS.Rd:340): Warning: <h4> anchor "BUG-FIXES" already defined
NEWS.html:638:1 (inst/NEWS.Rd:348): Warning: <h4> anchor "BUG-FIXES" already defined
NEWS.html:657:1 (inst/NEWS.Rd:357): Warning: <h4> anchor "NEW-FEATURES" already defined
NEWS.html:684:1 (inst/NEWS.Rd:372): Warning: <h4> anchor "USER-VISIBLE-CHANGES" already defined
NEWS.html:712:1 (inst/NEWS.Rd:386): Warning: <h4> anchor "NEW-FEATURES" already defined
NEWS.html:728:1 (inst/NEWS.Rd:396): Warning: <h4> anchor "BUG-FIXES" already defined
NEWS.html:764:1 (inst/NEWS.Rd:414): Warning: <h4> anchor "USER-VISIBLE-CHANGES" already defined
NEWS.html:817:1 (inst/NEWS.Rd:454): Warning: <h4> anchor "BUG-FIXES" already defined
NEWS.html:865:1 (inst/NEWS.Rd:489): Warning: <h4> anchor "USER-VISIBLE-CHANGES" already defined
NEWS.html:886:1 (inst/NEWS.Rd:499): Warning: <h4> anchor "USER-VISIBLE-CHANGES" already defined
NEWS.html:903:1 (inst/NEWS.Rd:508): Warning: <h4> anchor "BUG-FIXES" already defined
NEWS.html:919:1 (inst/NEWS.Rd:517): Warning: <h4> anchor "NEW-FEATURES" already defined
NEWS.html:950:1 (inst/NEWS.Rd:534): Warning: <h4> anchor "USER-VISIBLE-CHANGES" already defined
NEWS.html:991:1 (inst/NEWS.Rd:558): Warning: <h4> anchor "USER-VISIBLE-CHANGES" already defined
NEWS.html:1003:1 (inst/NEWS.Rd:564): Warning: <h4> anchor "NEW-FEATURES" already defined
NEWS.html:1020:1 (inst/NEWS.Rd:573): Warning: <h4> anchor "BUG-FIXES" already defined
NEWS.html:1047:1 (inst/NEWS.Rd:589): Warning: <h4> anchor "BUG-FIXES" already defined
NEWS.html:1067:1 (inst/NEWS.Rd:601): Warning: <h4> anchor "USER-VISIBLE-CHANGES" already defined
NEWS.html:1092:1 (inst/NEWS.Rd:615): Warning: <h4> anchor "BUG-FIXES" already defined
NEWS.html:1109:1 (inst/NEWS.Rd:625): Warning: <h4> anchor "USER-VISIBLE-CHANGES" already defined
NEWS.html:1130:1 (inst/NEWS.Rd:637): Warning: <h4> anchor "NEW-FEATURES" already defined
NEWS.html:1149:1 (inst/NEWS.Rd:646): Warning: <h4> anchor "BUG-FIXES" already defined
NEWS.html:1186:1 (inst/NEWS.Rd:665): Warning: <h4> anchor "USER-VISIBLE-CHANGES" already defined
NEWS.html:1214:1 (inst/NEWS.Rd:681): Warning: <h4> anchor "NEW-FEATURES" already defined
NEWS.html:1227:1 (inst/NEWS.Rd:688): Warning: <h4> anchor "BUG-FIXES" already defined
NEWS.html:1266:1 (inst/NEWS.Rd:707): Warning: <h4> anchor "USER-VISIBLE-CHANGES" already defined
NEWS.html:1278:1 (inst/NEWS.Rd:713): Warning: <h4> anchor "BUG-FIXES" already defined
NEWS.html:1293:1 (inst/NEWS.Rd:720): Warning: <h4> anchor "USER-VISIBLE-CHANGES" already defined
NEWS.html:1305:1 (inst/NEWS.Rd:726): Warning: <h4> anchor "BUG-FIXES" already defined
NEWS.html:1338:1 (inst/NEWS.Rd:743): Warning: <h4> anchor "USER-VISIBLE-CHANGES" already defined
NEWS.html:1349:1 (inst/NEWS.Rd:748): Warning: <h4> anchor "NEW-FEATURES" already defined
NEWS.html:1364:1 (inst/NEWS.Rd:755): Warning: <h4> anchor "BUG-FIXES" already defined
NEWS.html:1387:1 (inst/NEWS.Rd:768): Warning: <h4> anchor "USER-VISIBLE-CHANGES" already defined
NEWS.html:1399:1 (inst/NEWS.Rd:774): Warning: <h4> anchor "NEW-FEATURES" already defined
NEWS.html:1420:1 (inst/NEWS.Rd:787): Warning: <h4> anchor "BUG-FIXES" already defined
NEWS.html:1446:1 (inst/NEWS.Rd:801): Warning: <h4> anchor "CRAN-COMPATIBILITY-UPDATES" already defined
NEWS.html:1464:1 (inst/NEWS.Rd:809): Warning: <h4> anchor "NEW-FEATURES" already defined
NEWS.html:1509:1 (inst/NEWS.Rd:834): Warning: <h4> anchor "USER-VISIBLE-CHANGES" already defined
NEWS.html:1552:1 (inst/NEWS.Rd:859): Warning: <h4> anchor "BUG-FIXES" already defined
NEWS.html:1592:1 (inst/NEWS.Rd:882): Warning: <h4> anchor "NEW-FEATURES" already defined
NEWS.html:1617:1 (inst/NEWS.Rd:897): Warning: <h4> anchor "USER-VISIBLE-CHANGES" already defined
NEWS.html:1634:1 (inst/NEWS.Rd:906): Warning: <h4> anchor "BUG-FIXES" already defined
NEWS.html:1675:1 (inst/NEWS.Rd:927): Warning: <h4> anchor "BUG-FIXES" already defined
NEWS.html:1699:1 (inst/NEWS.Rd:940): Warning: <h4> anchor "BUG-FIXES" already defined
NEWS.html:1739:1 (inst/NEWS.Rd:963): Warning: <h4> anchor "BUG-FIXES" already defined
NEWS.html:1787:1 (inst/NEWS.Rd:993): Warning: <h4> anchor "MINOR-USER-VISIBLE-CHANGES" already defined
NEWS.html:1842:1 (inst/NEWS.Rd:1028): Warning: <h4> anchor "NEW-FEATURES" already defined
NEWS.html:1874:1 (inst/NEWS.Rd:1050): Warning: <h4> anchor "MINOR-USER-VISIBLE-CHANGES" already defined
NEWS.html:1908:1 (inst/NEWS.Rd:1070): Warning: <h4> anchor "BUG-FIXES" already defined
NEWS.html:1936:1 (inst/NEWS.Rd:1086): Warning: <h4> anchor "MINOR-USER-VISIBLE-CHANGES" already defined
NEWS.html:1950:1 (inst/NEWS.Rd:1094): Warning: <h4> anchor "BUG-FIXES" already defined
NEWS.html:1967:1 (inst/NEWS.Rd:1104): Warning: <h4> anchor "BUG-FIXES" already defined
NEWS.html:1989:1 (inst/NEWS.Rd:1117): Warning: <h4> anchor "USER-VISIBLE-CHANGES" already defined
NEWS.html:2009:1 (inst/NEWS.Rd:1127): Warning: <h4> anchor "BUG-FIXES" already defined
NEWS.html:2050:1 (inst/NEWS.Rd:1150): Warning: <h4> anchor "BUG-FIXES" already defined
NEWS.html:2087:1 (inst/NEWS.Rd:1174): Warning: <h4> anchor "MINOR-USER-VISIBLE-CHANGES" already defined
NEWS.html:2141:1 (inst/NEWS.Rd:1206): Warning: <h4> anchor "MAJOR-USER-VISIBLE-CHANGES" already defined
NEWS.html:2183:1 (inst/NEWS.Rd:1236): Warning: <h4> anchor "MINOR-USER-VISIBLE-CHANGES" already defined
NEWS.html:2228:1 (inst/NEWS.Rd:1265): Warning: <h4> anchor "NEW-FEATURES" already defined
NEWS.html:2332:1 (inst/NEWS.Rd:1323): Warning: <h4> anchor "BUG-FIXES" already defined
NEWS.html:2391:1 (inst/NEWS.Rd:1360): Warning: <h4> anchor "MAJOR-USER-VISIBLE-CHANGES" already defined
NEWS.html:2424:1 (inst/NEWS.Rd:1381): Warning: <h4> anchor "NEW-FEATURES" already defined