I am saving into my Documents folder and am getting this message sporadically.

Same issue: constant "modified outside of Illustrator" warnings at every save.

Early 2015 MacBook Pro running 10.13.1. (Seems to have started after my recent upgrade to High Sierra.)

I've only kept notes on the last couple files, but the issue seems to occur on all files. It's happened on at least two local files and one file that was on an attached physical drive.

I don't think any have had linked assets. If they did, they definitely wouldn't have been linked to any cloud services.

I get this message all the time too. I was not aware it was due to saving it to Dropbox, but it does appear to be the case when i investigated after reading the comment.

Me too recently upgraded to HS.

I don't use Dropbox and get this message constantly.

Adobe CC up-to-date. MacPro (late 2013) running OS High Sierra. The only software running besides Finder is Photoshop, Illustrator, Bridge, Linotype Font Explorer X Pro (up-to-date), and Chrome browser.

Also experiencing a whole bunch of other little annoying things since updating to High Sierra... Often the command(+) keyboard shortcut for zoom simply stops functioning in Illustrator (sporadic - function returns after using the zoom tool).

Most annoying is that all the standard Finder functionality/shortcuts no longer work in Bridge... Pressing a letter key does not advance to files beginning with that letter, keyboard shortcuts (like duplicate file) are non-functional, Return key does not work (when renaming files for example), and my personal peeve... the space bar does not function as a quick file preview... you're forced into the command-L slideshow mode to simply preview a file. Cumbersome and highly annoying.

This is a new problem for me since updating to 10.13. I am not using Dropbox or Google Drive. My files are saved to the desktop.

I have been having this issue since updating to 10.13.1. My files have no links, no fonts, etc. and are saved locally.

Same issue here: "file has been modified outside of illustrator" message each time I save this one file - it doesn't happen with every ai file I'm working on. I have Placed .tif files in the ai document that gives me the error. I am saving it locally (not Dropbox). I just upgraded my OS to High Sierra about 2 days ago.

10.13.1 and having the problem saving to internal MacBook pro drive.

just updated Mac OS and I have had the problem continuously since then, just saving to my hard drive. SUPER ANNOYING!

Same problem as Evelyn: After upgrading to High Sierra and the latest Adobe updates. I am saving to my internal SSD drive (with Time Machine backups to an external WD drive). I also longer have thumbnail images for InDesign, which I updated on 11/17/17. I only get the product logo. Illustrator and Photoshop thumbnails are fine (updated 11/2 and 11/14, respectively).

ALSO DRIVING ME NUTS.

same here. and i'm working with files in my desktop - no pen drives or similar.

Hello. Will there be a reply to all those comments? I have the same issue even just saving to my hard disk.

I'm getting the same issue Illustrator CC 2018 22.0.1 Mac OS 10.13.1

Getting the same issue during Save. High Sierra 10.13.1 + Illustrator 22.0.1. No external drives.. Just saving on computer hard drive. Error seems very intermittent, but keeps popping up.

Seems to be after upgrading to High Sierra and doing the latest Adobe update on 11/17/17. I am saving to my external Seagate drive right next to me. The other problem is that I no longer have thumbnail images for Illustrator ai or eps or Photoshop psd files. I only get the product logo. Please give us some solution. It's driving me nuts.

Also applies to files being sync'd with a Box.com account

I updated Illustrator (22.0.1) and my OS to 10.13.1 about the same time, and the issue occurs while working on files located on a local Thunderbolt RAID array.

I'm getting the same issue with Illustrator CS2018 on 10.13.1. I'm saving opened/worked on files onto an exterior drive which is formatted as Mac OS extended (journaled). It's doesn't always happen every time I save and I haven't been able to replicate what triggers it. I doesn't appear to cause a problem with my files other then being annoying extra step.

It started for me after installing High Sierra. A file worked on and saved several times before the installation - with no problems. I just tried a "save as" for same file with same name, and have changed it 3 times since then without repeat of the problem. No guarantees but worked for me.