I had the same issue but seemed to find a temporary fix by saving one of the preset color settings into the same folder that ACEConfigCache2.lst is stored in.

Here's what has worked for me so far:
1. In Illustrator, go to edit » color settings
2. From the Settings dropdown menu, select the same color setting that Photoshop is set to (for me it is North America General Purpose 2)
3. Then hit the "Save..." button just to the right of the dropdown menu
4. Save the setting into the same folder where ACEConfigCache2.lst is located (Users » (your user folder) » Library » Preferences » Adobe » Color
5. Quit Illustrator and restart

So far I haven't had any further issues, whereas previously (after the most recent update 25.2.1), the color settings always reset to Emulate Adobe Illustrator 6 within minutes of restart.

Hoping this continues to work and helps others and that Adobe permanently fixes the problem.

@Karlis the fix does not work! As soon as one opens Photoshop again, all settings are reverted to "Emulate Adobe Illustrator 6.0". Such as mess Adobe!

Your great fix has disappeared in 25.2.1 again! It's so annoying

I have the same problem too - AI 25.2.1 & Bridge 11.0.1.109

My first time with this problem after updating to the latest Illustrator 25.2.1 this morning and can't find what my original setting were. Tried all the fixes but any files I open now start by telling me the wrong profile is set. Definitely a pain especially as I'm paying £50 a month for this now!

This was the solution for me!

1. If you use an Adobe supplied Color Settings preset, go to next step, otherwise use Photoshop Color Settings, to create your desired color settings, and then Save a named Preset.

2. Quit all Adobe apps

3. Hold down the Option key, and choose the Go Menu.

4. Chose Library.

5. Go to Preferences/Adobe/Color

6. Delete or move this file: ACEConfigCache2.lst

7. Go into Bridge, and go to Edit, Color Settings, and chose your desired preset, and click Apply. If done in Bridge 2018, you don't need to do it in Bridge.

8. Quit Bridge, and now all your Adobe apps will be "Synchronized" and will not revert back to the factory defaults!

I have an up-to-date Mac and current Creative Cloud subscription. I came close to losing a client over the color shift in long gradients of neutral gray that were suddenly appearing reddish on calibrated monitors. (Other recent documents have bright saturated colors, so the color shift was not apparent. Bridge color settings did not fix anything.

A complete uninstall (including any presets and preferences) and brand new install fixed the problem only until I also opened Photoshop. Fortunately, I carefully rechecked Illustrator document's color settings and was able to reset color preferences to the offset values I wanted....which lasted not much longer than it took me to save the document and deliver it.

This situation is unacceptable. Please fix the problem with the next dot update. Thanks.

STOP ADDING COMMENTS..
read the solution:
david vincent commented · November 15, 2018 7:51 PM

Or just delete Library/Preferences/Adobe/Color/ACEConfigCache2.lst
And then change colorsettings as you want.. it works..

iMac (21.5-inch, Late 2013)
Processor 2,7 GHz Quad-Core Intel Core i5
Memory 16 GB 1600 MHz DDR3
Graphics Intel Iris Pro 1536 MB

The same here. I see that COLOR SETTINGS changes when I work with PhotoShop and Illustrator together.

I've tried to sync through BRIDGE but it doesn't work. Always comes back to EMULATE ADOBE ILLUSTRATOR 6.0

having the same problem - I have downgraded photoshop to version 22.2 and its still happening - I need a work around!

I confirm that downgrading Photoshop to version 22.2.0 allows you to avoid the problem.

Downloaded stability updates for both Photoshop and Illustrator made available by Adobe this AM (March 24), and the original color profile glitch that occurs when switching from Photoshop to Illustrator still persists, though inconsistently now. While before it <<always>> reverted my color profile settings to "Emulate Adobe® Illustrator® 6.0" when switching from Photoshop to Illustrator, now it only does it <<most of the time>>.

Please, Adobe, for the love of God and all that's good in the world, fix this asap.

Downgrading to Photoshop 22.2.0 solved the problem for now.

Good luck.

2021 - SAME PROBLEM IN ILLUSTRATOR 25.2.1 and in INDESIGN 16.1

- THIS PROBLEM IS BEING CAUSED BY PHOTOSHOP 22.3.0 - anytime Photoshop is launched or brought to the foreground, it overrides the color settings for Illustrator and InDesign (even if those apps aren't open).

PLEASE FIX THIS IMMEDIATELY!!!

Same Issue here with Version 25.2.1. Please fix! Adobe do your homework

Same problem here! How can I fix this?

Ditto to all of the above. Driving me nuts. Please fix ASAP.

Alllooo Adobe, currently experiencing the same issue and all applications are up to date.

Same issue here, very frustrating having to change every time I switch between Photoshop and Illustrator. Please fix.

Same problem here.
iMac 27 inch 2019
Intel core i9 3,6 ghz
32 gb ram
I saw that the problem shows up when photoshop is in use. If I don't use photoshop the problem doesn't arise.
Someone please tell adobe not to waste our time with these buggy update. At each update they find serious ones