The first thing I would do is install an older version using the CC app (and make sure to have many backups of these critical files)
I have just encountered this issue today. It sucks that the IT team never respond promptly, and most of the answer are just copy and paste the guides.
Anyway, I assume this is a bug due to different versions of the software. Like what Ton_Frederiks saif below, install older version of the app, and open the file from it.
Or download Infinity Designer, and open from that app instead.
I hope this helps.
This has happened to me three times in the past week, something I'd never seen before. I'm using Illustrator 2019, 23.1.1, and macOS Mojave 10.14.6. The files are stored on a windows-based server. Illustrator 2019 opens most of the illustration, missing some upper layers. Illustrator 2020 opens just the PDF data, which is all there but is a nightmare to have to edit.
Every time, Adobe has been able to quickly recover the files for me, but it's nuts that this keeps happening. Two other illustrators here use the same setup, but never encountered this issue, and no server issues with several designers using InDesign.
This is humbling, but I think I found the problem. Our file server was full. Usually, Illustrator would give us an error when this happened, but not lately. I'll report back if it turns out that this isn't the cause.
the documents you have are most likely already corrupt.. to take advantage of various automatic recoveries being developed in illustrator upgrade to latest.. or atleast above 24.1..
share a sample file to be looked into by the community.. or share at firstname.lastname@example.org..
finally in case you are able to open the file correctly in some version of illustrator do mention the version.. let adobe folks know in which update they broke your file open.
Hi! Hope you've found some way around this by now. If not, I've discovered that Illustrator won't let you open objects exported from another program (e.g. rhinocerous in my case) if the name of the layer of the object has a special character. For me, the name of the layer in rhino was "balcony/" literally because I missed the enter key and was too lazy to go back and correct it, and it cost me an hour of trying to figure out why the object wouldn't read. I took out the "/" and it read it straight away. This is so stupid and it's beyond me why Adobe hasn't discovered/made a statement about this yet.
this comment literally saved me!!!! Thank you so so much :') It's my finals week and I have no idea why my files keep getting these messages! Thanks again!
I solved this problem this way.
Edit > Preference > Plug-ins & Scratch Disks > Primary - C:\(or D\), Secondary - C:\(or D\)
I hope this helps.