I have well over 20 sites that I manage and am beginning to upgrade. All of my sites are currently running 7.4.2. I have completed four so far; 2 successes and 2 failures on the upgrade process itself. The upgrades are stopping/freezing (50-51%) at the HTML module update. If I restart the upgrade, it proceeds to the supposedly upgraded site, but nothing past and including the HTML module has been updating. I now have to update all the core modules manually; a real pain in the next and very time consuming. 

I decided to interrogate the differences in the successes and failures and I found something that is very repeatable. I recall that a previous issue was introduced in DNN regarding not having a "zero" (0) portal for a specific installation. Perhaps it was from 6.x to 7.x. Regardless, the "temporary" solution was to create a "zero" portal record in the portals table. All of my failed sites have no real "zero" portal; but they all still have the phantom 0 record in the table. What I'm not clear on is whether the 0 database entry is still required or not; and if it or the fact that there isn't a 0 portal still interfering with this upgrade; specifically with the HTML module update part. 

I would love for someone much more technical than me from DNN to try an upgrade with a site having no portal 0 and tell me what you find. 

Now, what do you suggest I do to resolve this issue? 

Thank you, 

James