If you’ve installed Mojave, you’ve likely seen warnings about Amazon’s KindleGen utility, which has not been optimized for current versions of macOS. As those warnings inform, older 32-bit programs like KindleGen won’t run in Catalina, the forthcoming version of macOS.
We’ve received many questions about whether Amazon will publish an updated 64-bit version of KindleGen in time for the release of Catalina, due this fall. We don’t know the answer to that. What we do know is that KindleGen hasn’t received an update since 2013, and shows many signs of being abandoned by Amazon.
Given this, Vellum will soon move away from using KindleGen entirely. Instead, Vellum will produce a Kindle-specific EPUB file.
You should find this makes little difference to your workflow. When you’re ready to publish, you’ll be able to upload this file to KDP without any extra conversion; your readers won’t see any difference. To proof your book beforehand, you can open this file directly in Kindle Previewer. And in situations where you do need a mobi file (to send an ARC, for example), you can make use of the Export command in Kindle Previewer.
By avoiding KindleGen, you’ll find generation to be much faster, more reliable, and free of any warnings about 64-bit compatibility.
This change will be released in the next update to Vellum, due in early September, and well before the release of Catalina. We’ll have more details at that time.
Have questions? Get in touch.
Update 10/02/19: Mobi output is again available in Vellum 2.6.2.