My Illustrator files opens as XD files and I can't change it

I'm on windows 10 BTW..

1. Uninstall both illustrator and XD

2. Reinstall illustrator

3. Restart you PC (additional step)

3. Check your illustrator files.. should see the ai icon now - don't proceed to step 4 until you do. ( if not restart again or go into windows as instructed above)

4. Reinstall adobe XD

Hope it helps

Had exactly the same problem in Windows 10 and this fixed it for me.  My problem:

• I copy/paste vector information in Illustrator and paste it into Photoshop as a smart object.
• When I double-click the smart object layer, it opens in Adobe XD (which I recently installed) instead of Illustrator.

To open smart vector objects from Photoshop in Adobe Illustrator:

• Hit the Windows Key and type default, and select Default Apps
  :
• Click on Choose default applications by file type at the bottom of the window that opens:
  
  
• Find all your common vector file formats and select Adobe Illustrator as the preferred software (in my case, .ai & .svg):
  
  
  

Really hope this works for you.  Worked a treat for me ^_^

Changing the registry to 23 didn't work for me in itself. However, when I did that, I was able to change the file association in settings to ai, which I wasn't able to do before. It has stuck through several reboots, so I feel that I have solved the problem on my system.

Thanks everyone who helped on this issue.

I have since rebooted and all of my file associations are still proper.

Windows 10 64-bit

Well, this morning, none of the fixes are working for me. When I booted up, all the .ai associations had gone back to .xd. I tried the regedit change, no love. I uninstalled and reinstalled AI, no love. I again tried the regedit fix (reinstalling AI had changed it back to version 22), again no love.

To heck!

I just noticed this.

I right-clicked on an offending file

Went to properties

Hit change next to Open with

Selected AI

All better. 

Doesn't sound like it is working for most, but fixed mine.

Shouldn't have happened in the first place.  There are more and more of these little "issues" getting pushed to the public.  Too bad.

I checked my registry files > Computer\HKEY_CLASSES_ROOT\.ai and it said Adobe.Illustrator.22 but Adobe.Illustrator.23 is installed... changed that registry key to the latter and it seems to be fixed.

As a test, I uninstalled Illustrator leaving XD installed. I then reinstalled Illustrator and it changed the file associations for ai files to Illustrator. So far so good.

Can someone else try this and see if they can repeat my results.

I have had this problem since the update from 2018 to 2019, Nothing fixes this issue.  I uninstalled and reinstalled twice, rebooting etc; manually set the file associations several times and illustrator file extension still is set to XD CC; not only that but windows will not even let me change any file association of any Adobe file extensions; would not even let me associate Illustrator with the .AI extensions when Illustrator was the only Adobe app installed; spoke with live chat an hour ago, and they actually told me that no one else has ever had this problem. ermm  this is so obviously a bug in the 2019 update and a very detrimental to production times; this is an update that is industry crippling and deserves a rapid public response, not a denial of its existence.   (yes industry crippling, so if it takes 3-4 additional steps to complete a task, and those additional steps take 5-10 seconds to complete each time they need to be executed, you could be looking at a lose of several hours a day on production, which means lose of money) but i am just angry that the chat support actually told me I was the only one in the world to report this problem, and that he was an expert in Windows and Adobe asking me "have I tried to reboot my computer", I told him yes I know where the power cord is.....  ( FYI: all the answers to resolve this problem in this forum would work if there was no problem with Adobe )

Having the same problem here. It started when I updated the programs last October 18, 2018. The correct answer above is not working for me either. Any answers from adobe?