Will a critical prevent rt from running?

Short version:

Will this stop rt 4.4.1 from running:
[critical]: RT::Interface::email::Auth::MailFrom does not implement RT::Interface::email::Role. Mail plugins from RT 4.2 and earlier are not forward-compatible with RT 4.4. (/opt/rt4/sbin/…/lib/RT/Interface/Email.pm:293)

Long version:
As posted elsewhere, I have a dev/test server running a pair of 4.2.12 instances, they run just fine. I’m also using that server to test/prep for upgrade to 4.4.1. I have had many travails, but finally got the new instance to run… I think. I can’t bring up the web client through apache, but I can start the instance using the PSGI webserver, or at least it appears so, using netstat I can see something listening on the port I started rt on where before there was nothing listening.

The only entry in the rt.log is posted above. No errors noted in the apache error_log other the one posted by the rt (same as above)

We had determined that there was a dns issue, but that has, in theory, been corrected. The older 2 instances have been running fine for oooh long time. I can’t get this instance to come up in the browser, getting “This page can’t be displayed” error.