The File is an Unknown Format and Cannot be Opened error in Illustrator

[fullofproblems]

I recovered my Illustrator files from a hard drive and now none of them work. Just says "unknown format and cannot be opened." Tried all the tips in the Adobe website. No success. I want to recover everything in vector. 

[Mylenium]

Impossible to say anything. You have not provided any system info and critical details like how the original files were created and saved vs. what version of AI you use currently and other such stuff.

Mylenium

[fullofproblems]

They were just saved normally as .ai. I use 2019 version. The hard disk was accidentally formatted and I used a recovery software to get them back. Of course, I suspect the recovery tool didn't do a good job of recovering the files. Some recovery services managed to pull out some layers, but I want everything intact as vector. 

[Monika Gause]

Can you open them in Acrobat?

If that works, then you might be able to recover at least something.

But that just might be caused when recovering a harddisk. Make backups next time.

[fullofproblems]

I can't. It just says file not supported. Some paid services extract some things, but the vectors are a clustered mess. 

[Monika Gause]

If you need to investigate you might try and open the files in a text editor, compare them to working files and copy over parts that are obviously missing, but that might perhaps not lead to any success.

[derekwatson]

Is the data in the first few lines to help with this, not confident about doing this

[Monika Gause]

This method is only a last resort.

The best method is to always make backups.

[derekwatson]

I have a Time Machine Backup, Clone Backup, Backblaze backup, and a copy on a Drobo... All versions of the same handful of files give the same error!

[Monika Gause]

Did you also update the system? Or just Illustrator?

When was your last computer reboot?

Did you reset the preferences after updating Illustrator?

[derekwatson]

Updated to new MacBook Pro, Mac OS is up to date as is Illustrator. Reboot yesterday and tried with new prefs today. It's only a handful of files but unfortunately ones I need to access. Odd that all backups are giving same error. 

[Monika Gause]

Can you have a coworker open those files?

What is the history of those files? With which version did you create them? Where did you save them? Do they have anything in common? Fonts, placed images, ...?

[derekwatson]

I am getting the same issue with some files since 2020 update. Have tried in Acrobat but no luck either.