OK: seems the issue is a cosmetic one, but none the less annoying:
according to the last two lines of the DA_Actions.xml:
<action id="63" type="Import" pkgFile="ngm_upgrade_wrapper_995000497_1.tgz" src="WEB_UI" started_on="Tue Jun 8 14:40:56 2021" completed_on="Tue Jun 8 14:40:59 2021" completion_status="success" />
<action id="64" type="Install" pkgFile="ngm_upgrade_wrapper_995000497_1.tgz" src="WEB_UI" started_on="Tue Jun 8 14:40:57 2021" completed_on="Tue Jun 8 14:41:12 2021" completion_status="failure" />
</completed>
<uncompleted>
< />
</uncompleted>
</actions>
and
[Expert@CPMGMT:0]# cat install_UpgradeTools_UPG_TOOLS_R81_7.log
[2021-06-08 - 14:41:07][10647 17897]:Testing file: /var/log/CPda/repository/CheckPoint#UpgradeTools#All#6.0#5#3#UPG_TOOLS_R81#995000497/ngm_upgrade_wrapper_995000497_1.tgz >>> tar=yes, gzipped=yes
[2021-06-08 - 14:41:07][10647 17897]:About to execute command: nice -n 19 gtar -zxvf /var/log/CPda/repository/CheckPoint#UpgradeTools#All#6.0#5#3#UPG_TOOLS_R81#995000497/ngm_upgrade_wrapper_995000497_1.tgz -C /var/log/CPda/repository/CheckPoint#UpgradeTools#All#6.0#5#3#UPG_TOOLS_R81#995000497/rpm
[2021-06-08 - 14:41:07][10647 17897]:-- extraction completed successfully --
[2021-06-08 - 14:41:07][10647 17897]:Installed upgrade tools build (995000497) >= new build (995000497), not installing ngm_upgrade_wrapper_995000497_1.tgz
[Expert@CPMGMT:0]#
when the WebUI is still spinning the wheel.
So had to terminate the WebUI session to get out of it.