Please get in touch with us at any of the other support channels – https://helpx.adobe.com/support.html . Since this is not a generic issue that we can reproduce at our end, we will need someone to look into your machine to figure out what is going on here.
Before you do that are you manually able to change file association of .ai file to another application say Notepad.exe ? There is another issue with file association going around. Please check this link: https://www.howtogeek.com/fyi/microsoft-broke-windows-10s-file-associations-with-a-botched-update/
79 votes70 comments · Illustrator Bugs » File Save, Import and Export · Flag idea as inappropriate… · Admin →
We have this issue fixed, please refer to steps below to solve the issue
XD defaulting to AI on Windows
- Please update to latest version of XD (13.1.32) to resolve the issue. Thank you XD engineering team for solving this issue.
PS defaulting to AI on MAC
- Please update to latest version of Illustrator (23.0.1) to solve this issue.
An error occurred while saving the commentSven Lewerentz commented
Updating XD does not fix it here (Windows 10). Still can't open Vector Smart Objects (now I get the error message "Das ursprüngliche Smartobjekt konnte nicht bearbeitet werden, weil die Anwendung, in der das Smartobjekt erstellt wurde, nicht gestartet werden konnte") and still can't select Illustrator as default for .ai files.