Seda, and why do you think it is a bug?
If you want to modify spacing for a selection in a text, you should use tracking indeed. Kerning is a thing you tweak for pairs (also you can also set it to 'Optical', I wonder why Ai doesn’t say this).
Can you provide exact steps you are trying to do or record a video? And what is your intention behind it? What are you trying to do?

Mac Monterey 12.5.1
version 26.5
I changed the font type but the same warning keeps appearing.

just installed the newest version AI 2020 v24.2, this still happens wtf, i try it on my circle text

now on cc24.1 and STILL NOT FIXED, please take care of business Adobe! we re paying for it!

cc 24.1 has the SAME issue, you can't expect us to use 22.1 as a fix, please take care of it.

This will crash Illustrator (and InDesign and Photoshop) every single time without fail, all cc 2020 apps I've tested, specifically:

InDesign 15.0.2, Illustrator 24.1, Photoshop 21.1.2

I'm using OSX 10.15.3 Catalina

Try this:

–add a font to ~user/Library/Fonts/MyFontFolderName/ to install. Works with any font, but for example try Adobe's own wonderfully designed Source Serif Pro
–make a new document in Illustrator, set some text in that font, eg: Source Serif Pro-Regular, save document (or don't save, same result)
–move the font file, eg: SourceSerifPro-Regular.otf to a sub folder, eg: ~user/Library/Fonts/MyFontFolderName/AnotherFolder/
–app will crash EVERY SINGLE TIME.

Once again, this happens with every font I've tried, fonts I've designed, fonts from Adobe originals, fonts from other foundries. Happens with OTF, and with TTF. I'm a type designer and I'm testing out new versions of fonts many times in a day, even many times in an hour, so this is very frustrating.

FWIW, this only seems to affect Adobe apps. Other apps like Apple's TextEdit or Pages aren't affected by this at all.

A normal user action like this, re-arranging font folders, shouldn't cause all Adobe Apps to crash every time. Please consider this a very high priority and fix ASAP. Thank you!

I have just run into this issue in the middle of working on a file. It went from working for the first 25 minutes on the file to getting this error. I just did the update and the issue is still there.

How do I fix this????

I have this issue now after the recent update

Not available at all. Illustrator latest as of Feb 14, 2019 still doing this idiotic thing. Why is Illustrator being made clunkier and clunkier??

same here, I´d rather ***** this *** software on a functional version than pay each month for a set of broken products!

It's back in 23.0.01 - What a pain

This is back in 23.0.1 - fix this for good already Adobe

Same here. Mac and I have an updated version of Illustrator.

Same issue again but on a PC

I am having the same issue as well

Kerning is no longer functional in the current update of Illustrator. A previous user had this problem and the response claims that the bug has been fixed, but it is still not working.

Whenever I try to adjust the kerning of letters, I get this error message:

"Kerning on extended selections can only be set to Auto or 0. To modify spacing between multiple characters, use the Tracking option.

I am running Illustration version 22.1.
My Mac runs system 10.12.6.

WHEN IS THIS GETTING FIXED?

All the issues with Type have NOT been fixed whatsoever. I've currently uninstalled the latest version of Illustrator TWICE. Once, without deleting all data and then again with deleting all data.

Still happening, I even uninstalled Ai and reinstalled but still can't kern properly.