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Adobe Illustrator/Illustrator CS5 unknown format



Recently I tried opening my Illustrator files and they will not open. A box comes up that says the file is in an unknown format. Even when I open Illustrator and try to open a new document, the message says " is in an unknown format." I tried using InDesign to place the Illustrator file and it says "no filter found for requested operation." What do I do? I need to use Illustrator and then I need to open those important files.


Normally this means that these are either not really .ai files. I've seen this when files are saved in another format and the extension changed outside of illustrator to .ai. The other issue I've seen that caused this is when files have been emailed without zipping and the email app or gmail has formatted to a txt file and then the extension is added back in.

If these are neither of the cases, let me know if you created these files on the computer you are opening them on and what version of AI and the OS you are running.



Adobe Illustrator

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Kevin Stohlmeyer


I am an Adobe Certified Instructor, Adobe Community Professional and Adobe Freelance Professional. I travel nationally speaking on Adobe Creative Suite applications, including Illustrator and design. I can answer questions about Adobe Illustrator version CS1 through the all-new Creative Cloud.


I am an Adobe Certified Instructor for Adobe Illustrator and have been teaching this software in college/higher education and for an Adobe Authorized Training Center since 2000. I have been an active user of Adobe Illustrator as a professional graphic designer since 1994. I am also the author of the Adobe Illustrator Certified Expert Exam. I am a published author for Adobe Inspire Magazine, writing articles on Creative Suite applications including Photoshop, Illustrator and the Adobe Touch apps.

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