Had the same issue immediately after upgrading. Also get the not enough RAM dialogue box as well. I have also had issues with trying overprint preview. One time I had a file with 2 spot colors, it told me I couldn't use overprint preview because there were over 27 spot colors...

I wasn't able to find a workaround so I went back to V22.1 (March 2018 update). To go to previous version: Go into Creative Cloud. Next to illustrator there is a button that says open with an arrow to the right. Click the arrow then click manage > other versions. Install v22.1. Then you can uninstall the 2019 version (V23).

I am upgrading my Mac to Mojave to see if it fixes anything.

I'm having the same issue.

I am having the same problem with my brand new iMac Pro... I had this bug since updating to the new CC19

Same issue on MacOs Mojave 10.14. It did progressively get worse. Had to go back to the previous version. Please fix this issue soon. Need to stay up-to-date in my office.

Updated this morning I have the same issue I'm on windows 10 system. Was working fine before the update.

Got in touch with Raghuveer Singh, and he and the Adobe bug team are on it. I gave him a test file, along with display and system details so they can get further to the bottom of the issue.

I don't know how they let a bug like this pass through. The stranger thing is my co-workers aren't experiencing the bug. Only my machine is dealing with it, and we're a team of 8 designers. One of my co-workers claimed they experienced the bug, but after updating to Mojave, it went away. Not for me! Anyway, hoping they fix this sometime this week. Might be longer, though.

Same issue daily on my iMac 27 OS 10.13.6, "Can't finish previewing." I restart and hope my files are still there. They have been there, back to the last Save. I'm not going back to 2018 though.

Same issue. Went back a version to 2018 for all Adobe programs as a temporary fix.

I'm having the same issue.

I'm having the same issue.

Same problem, it is getting more frequent now. Almost unusable.

Same problem, not enough RAM to open ai files, have to restart program constantly.

Exactly the same issue, this is so frustrating. I have High Sierra, working on a mid 2012 MacBook Pro. No issues before the update.

I solved it with reinstalling previous version.
http://prntscr.com/l8zcah

Very disappointed, adobe.

how do you reinstall the previous version of illustrator?

I wonder: Is Adobe testing their software before launching it?

Yep, same, v23 also. Never had this issue before in 20 years! But even on basic files it's happening daily.

Same problem here, working with old version until problem is solved.

same problem? is there any update on this issue