The one that opens for me when a file gets double-clicked is Beta, because it was installed last :/ it’s something Windows does and the only way to change it it to reinstall GA build. When I try to do these steps — still doesn’t happen for me!
Can you at least show or tell what fonts do you get? do the names change or do they change only visually?

you have to double clic the file with illustrator closed
if illustrator is alredy open you don't see the problem

1 quit illustrator
2 double clic the file (don't worry opening fonts)
3 save with new name
4 reopen the file

Alas, Marco, can’t reproduce it.
This is what tried:
1. Opened the file with 29.8.1 and installed the missing fonts
2. Saved it under a new name(with no font embedding), closed the document
3. Double-clicked the file
The fonts are the same: Espiritu Condensed and Mislab Std Compact Demi
What do you get when these do change? Or do they change only visually, and the names stay the same?

hi all
I have something new about this issue
I have a file made with Illustrator 29.2
if I open the file on my mac with 29.8.1 and save with new name it is all ok 
but
if I have Illustrator closed and double clic the file that starts Illustrator and save with a new name
after reopen the new file the fonts are changed
 
I attach the file so you can try if you have the same result
I hope this can help to solve the problem

Not sure if this is related to the same bug, but... I noticed that, when reducing the size of a text box to less than the amount of text there is, the fonts simply invert between bold and regular on display, even if the fonts still register the correct one on the character menu. See the video attached. This is getting ridiculous!

sometimes when I open a file I have already worked on, fonts go missing even though I used them before closing the file.

Is there any update/bug fix /Work-around for this issue. We're using version 29.6.1 and this issue still persists. Like the other users we tried reverting back to 29.4 and it didn't resolve the issue.

Same issue with FONTS changing.. and also having this PLUG issue. and nothing seems to work to fix it. Version 29.7.1

Hi, can you share a file which shows the issue?

In the latest version of Adobe Illustrator, I often experience random font substitution issues when opening older files. The fonts are properly installed in my system, but Illustrator does not recognize them correctly.

For example, if I copy the same AI file 10 times and open each copy, Illustrator displays different random font substitutions each time. However, when I open the same files in an older version of Illustrator, the fonts display correctly without any issues.

This indicates that the problem is not caused by missing fonts, but rather by how the new Illustrator version handles font data in older documents.

Steps to Reproduce:
– Create a file in an older version of Illustrator with specific fonts.
— Open the same file in the latest Illustrator. Fonts are shown incorrectly or substituted, even though they are installed.
— Copy the same file multiple times and open each copy → the substitutions are inconsistent and random.

Expected Result:
Illustrator should recognize and apply the installed fonts correctly, just like in the older versions.

Actual Result:
Illustrator randomly replaces fonts with incorrect ones, even though the correct fonts are installed and available.

System Info:
OS: Microsoft Windows 11 Home
Illustrator version: Illustrator (29.7.1)
Fonts: Various fonts are affected, not limited to a specific family. For example: Montserrat, Anja Eliane, Questrial, Poppins, and many others. The issue occurs randomly with different fonts each time, even though they are all properly installed in the system.

I am also running the current version of Illustrator 29.7.1 and have just now had the issue reoccur

I've reopened the two files that have been affected by font swapping, and opening them in Beta 29.9 doesn't resolve this

Illustrator 29.7.1 on Mac Ventura 13.5.2 (22G91)

I dont' know whether it's related to this current issue, but now I have parts of my text that change appearance when I'm trying to change the Font weight of another part, or when I try to type more text.

The workaround I have found it copy-pasting the text into a new Textbox. But still, this needs to be fixed.

Still the same problem with the 29.7.1 version....

29.7 solved this issue for me.

I previously reported that the issue was not resolved in version 29.7, but this was my mistake (I was looking at a file that had been saved with the fonts already replaced). The problem has actually been resolved in version 29.7. I have already deleted the incorrect bug report I submitted earlier. Thank you to the development team for your efforts.

It just happened to me too (Illustrator 29.6.1 on Mac 13.5.2).

It happened only to the fonts I had replaced with the Find/Replace Fonts… tool. The others were OK.

I cannot find a way to replicate it, but there seems to be a bug that occurs randomly where Illustrator doesn't save the font selection on the document correctly. When re-opening properly saved files that are affected, the file will open, but the majority of text in the document having the incorrect fonts applied. In a production environment, this is extremely frustrating. This needs to be addressed immediately. I cannot post any examples as the examples have occurred on artwork for a company I work for, however, this bug has occurred on two separate occasions, and it is frustrating to have to redo work that has already been done.

I have the same issue with 29.6.1.
This is a big issue. In my case, it seemed to have correlated with 29.6.1 update.
Can we get advice on which version to downgrade to and an ETA for the solve?

I can't install the beta version right now so I can't test this, but i have a question: this fix corrects previously messed up files, or the fix only prevents this happening to other files?