"None of the selected packages could be updated"

The update manager came up, today, saying that Firefox had an update. After hitting "Install Update", I get a dialog:
No Package To Update`
None of the selected packages could be updated
firefox-52.2.0-1.el6_9.i686 requires libnspr4.so
firefox-52.2.0-1.el6_9.i686 requires libXext.so.6
firefox-52.2.0-1.el6_9.i686 requires libstdc++.so.6(GLIBCXX_3.4.9)
firefox-52.2.0-1.el6_9.i686 requires libstdc++.so.6(GLIBCXX_3.4.5)
firefox-52.2.0-1.el6_9.i686 requires libX11-xcb.so.1
firefox-52.2.0-1.el6_9.i686 requires libxcb.so.1
firefox-52.2.0-1.el6_9.i686 requires libgdk_pixbuf-2.0.so.0
firefox-52.2.0-1.el6_9.i686 requires libstdc++.so.6
firefox-52.2.0-1.el6_9.i686 requires libgio-2.0.so.0
firefox-52.2.0-1.el6_9.i686 requires libX11.so.6
firefox-52.2.0-1.el6_9.i686 requires libXfixes.so.3
firefox-52.2.0-1.el6_9.i686 requires libgcc_s.so.1(GLIBC_2.0)
firefox-52.2.0-1.el6_9.i686 requires libhunspell-1.2.so.0
firefox-52.2.0-1.el6_9.i686 requires libz.so.1
firefox-52.2.0-1.el6_9.i686 requires libnssutil3.so
firefox-52.2.0-1.el6_9.i686 requires libsmime3.so
firefox-52.2.0-1.el6_9.i686 requires libjpeg.so.62
firefox-52.2.0-1.el6_9.i686 requires libpangocairo-1.0.so.0
firefox-52.2.0-1.el6_9.i686 requires libsta... : Success - empty transaction