Fonts no longer available

I'm encountering this thread a few months after its first posting, while investigating why my InDesign projects are experiencing a significant number of freeze-ups, apparently the result of font non-activation projects.

Like many of you, I'm a book and newspaper designer, with a need to update legacy publications from time to time but also dependent on certain fonts week in, week out -- that suddenly disappear with no explanation, and a costly disruption to our deadlines. Whatever notification Adobe ever promised users they would provide if a font were discontinued doesn't seem to happen.   

Searching the Adobe Fonts page for a longtime favorite, Kepler, today brought up only a blank page.  And IMHO, Adobe Support has been useless. I understand that software companies don't always have control over the decisions made by foundries. But couldn't they at least keep loyal users in the loop?

Anyone else put out with Adobe's cavalier treatment of designers who have been, like me, users (and teachers) since Day One?  And to reply to the above frustrated inquirer, suddenly the problem does NOT seem "rare."

@Barb Binder provided the correct answer. Here's what it says on the Adobe website:

https://helpx.adobe.com/fonts/using/removed-fonts.html

Hi @motjuste101:

I guess I was lucky that the removals did not impact my work.

It sounds like Adobe explained that this wasn't a malicious removal to sabotoge our documents, or even something under their control:

We are occasionally obligated to remove fonts from the font library, typically at the request of the foundry. Removals may happen for a variety of reasons, including when a typeface is no longer available for licensing and distribution or when the font family has significant updates. For example, Alverata PE from TypeTogether was overhauled, retired, and replaced by the family Alverata.

—https://helpx.adobe.com/fonts/using/removed-fonts.html

The solution for your existing documents is to license the fonts directly from the foundry (https://www.linotype.com/488/gill-sans-mt-family.html), or in the case of Aida Book, I see it is available as a free download from several locations. Or update your styles to use a different font (and then carefully review the documents because the text will reflow). It's always a good idea to rely on the "based on" feature when you are setting up styles so that you can edit the parent level style(s) and the change will flow through all of the children styles. This will soften the blow, but doesn't eliminate careful review.

Looking ahead, if you find a font available through Adobe, you might want to download it to play with it and then, once you are sure it is the right font, be proactive and deactivate it and license directly through the foundry.

~Barb