1. I open and edit an Illustrator document that has missing linked files, and chose to ignore them
2. I edit the file
3. Without closing the document, I chose open latest, and (by mistake) click on the same document that's already open
4. When the missing linked file dialog reappears, I click "Cancel"

Bug: This causes the already open document to close without warning, despite it having been edited.

I tried to attach a screen recording but it didn't work. Here it is:
https://youtu.be/8ezkSHbfUFA

There are two similar, but slightly different entries on the topic:
1. Illustrator file closes without warning/saving if accidentally re-opened while canceling errors / relink prompts — http://illustrator.uservoice.com/forums/601447/suggestions/38381689
2. Do not allow save if multiple versions of same file is open in same computer — http://illustrator.uservoice.com/forums/333657/suggestions/44660700

There are two similar, but slightly different entries on the topic:
1. Do not allow save if multiple versions of same file is open in same computer — http://illustrator.uservoice.com/forums/333657/suggestions/44660700
2. Open file that is already open deletes unsaved changes without prompt — http://illustrator.uservoice.com/forums/601447/suggestions/33872917

Brittnie, does it still happen for you? I try and the file stays, doesn’t get replaced with an saved state.
Please comment back.

Lars, do you still have this problem happening?
When I check it, Ai just focuses the opened file, but does not read it anew from the drive, replacing the unsaved one.
Do you refer to a local file, not the one across a local network, or a cloud file?

Well, I suppose it was not an error message, but a warning you are going to loose the data...
Hope it will never happen to you again, but next time please try to capture it and share more details. Fingers crossed!

Sry, got an error msg after accidently opened same file which i was wrking on, once I click ok, the file updated to older update and lost all last update i did without saving. didn't take any screenshot. couldn't create same instance. if i come across the issue nxt time will share with screenshot. wil share screenshot if happens again.

Can’t confirm. If I open the same document form the explorer, while it is already opened and changed in Illustrator, it just gets activated for me there, no data gets lost :)
Can you please provide more info?
Does it always happen for you? Where do you store these files? Which version are you using? What is your OS specifically?
Does it happen in the Beta version, or in the released one only? Anything else that can help to reproduce it by the devs?

When I am working on the file (example file1.ai) and if I go to explorer and open the same file1.ai again, I m losing all the work I did on the already opened file and it opens the file fresh again.

Wow! I confirm this, indeed it does close the file! How did I miss it?

Come on and get it together guys, this has been hanging out since 2020 :/

It had a file (unsaved) from a client open in the application, you need to open another file from another client, with a huge amount of material already approved in it. Illustrator not only did not open the file, but saved what was open in its place!

If I try to open a file that is already open, and then cancel because I realize it's already open, it closes the open file without saving. This was not the protocol before, is easy to replicate by mistake no matter your experience level, adds no benefit, and carries huge risk--not to mention it just isn't the expected outcome. Canceling an open does NOT mean close. Please fix. Thank you!

When working on a file in AI, if you attempt to open the same file from the file explorer on Windows, any changes in the AI file are removed without warning, resulting in work being lost.

win 10 AI 24.2.3

Steps: (actual result)
1. Open file, work on it
2. File > Open Recent File > select the same file
3. Warning prompt for missing linked image > Choose Cancel (see attachment)
4. THE OPENED FILE WILL CLOSE WITHOUT SAVING

expected result:
It should ask if I want to open a file that is already opened, and when I click cancel on the missing file warning prompt, it should not close my working file, it should just cancel the open file in a new window option.

If you unintentionally open an Illustrator file to open it but realize it was one that was already open, it's possible to lose any changes you've made to that file without warning.

Steps to repeat:
1. Open a file that results in a dialog box to show before completely opening (mismatched color profile, missing links, etc).
2. Modify the document in some way, but do not save it.
3. Return to Explorer and open the file again.
4. When the Illustrator brings up a dialog box, click cancel instead of ok.
5. The document you had open will close without prompting to save.

Steps:

1) Try to open an already open file and get the "This document is already open; create another window for the document?" prompt.

2) Select "No"

3) Still get "Could not find linked file..." warning with "Replace / Ignore / Cancel" options.

4) If you select Cancel (most obvious selection as per above "No" don't open another version of this document), the original version of this file also closes, with no "Save changes" prompt or anything. Any changes are subsequently lost.

This is very unintuitive UX and is a very costly mistake to make.

This is critical bug and cause my job lost many times. When I use Illustrator with an unsaved document, I can’t open the same file. That means I can lose the data. I remember there was an alert if I open the same file or couldn’t have it opened in an older version.
For example, Photoshop can not open a same file if I use the data. So Photoshop does cover this issue. Please fix this bug asap !! Thank