Which new tab "app" do you have? Have you checked for an update for that "app"?

Mozilla has a Firefox add-on application to use the home page for each new tab. I updated today and now that existing application will not work with the newest version of Firefox.

When I click "+" to open a new tab, I want my home page displayed. It's very simple. How can I accomplish that?

https://addons.mozilla.org/firefox/addon/new-tab-override/

The ability to change the new tab page was removed since Firefox 41.0

The old Firefox 43.0 you appear to be using is not a upgrade.

There is a alternative option, you can place the Home icon on the toolbar and middle-click the Home button to open Homepage in a new tab.

Acemon said

Mozilla has a Firefox add-on application to use the home page for each new tab. I updated today and now that existing application will not work with the newest version of Firefox.

If you mean "New Tab Override" then that is not a application but a Extension. It is also not made by Mozilla as the vast majority of Extensions hosted at addons.mozilla.org are made by a third-party author or company.

Application versus Extension is a mostly-sterile distinction because the desired result in my situation is the same. If extension it is, would you be kind enough to provide a link?

James said

https://addons.mozilla.org/firefox/addon/new-tab-override/ The ability to change the new tab page was removed since Firefox 41.0 The old Firefox 43.0 you appear to be using is not a upgrade.

The version of Firefox I am using was what I downloaded from the Mozilla website about two hours ago. If there is a newer-new version, would you be kind enough to provide a link?

" The ability to change the new tab page was removed since Firefox 41.0"

Why? There seems to be quite a few people who are irritated by that somewhat irrational decision. I don't think it's unreasonable to ask for a feature that (most) other browsers include as standard.