How to 'upgradepkg' following security advisory instrux

Please forgive my ignorance. I have asked this before but never got a specific answer, only suggestions for 'upgrading entire system'. That is not what I want to do.

The latest 'security advisory', 3/13/2020 for mozilla-thunderbird-68.6.0-i686-1_slack14.2.txz, for slackware64 14.2, has the following specific instructions:

------------------------------------------------------------
Installation instructions:
+------------------------+

Upgrade the package as root:
# upgradepkg mozilla-thunderbird-68.6.0-i686-1_slack14.2.txz
------------------------------------------------------------

Rebooted, logged in as root, online, opened cmd window, entered command above: result, nothing. cursor drops to next line, blank.

Before: my thunderbird --version: Thunderbird 60.8.0

After: my thunderbird --version: Thunderbird 60.8.0

My /etc/slackpkg/mirrors has, for US, slackware64 14.2, uncommented:

http:////ftp.osuosl.org/.2/slackware/slackware64-14.2/

Near top of 'mirrors' file, instruction says to use only http, not ftp.

I've followed instructions exactly. What am I missing here?

Is this patch/update ONLY for 32-bit systems maybe? If so, my bad.

Well, maybe I missed the '64' needed to modify instruction line? Again, my bad. Going back to change it.. will report results.

Thanks, jrc