I just experienced this on my document. Using Adobe Illustrator 20204 v.28.7. Was applying a stroke on a shape and got the message "Can't finish previewing. Could not complete the requested operation." and the document turned into outlines. It fixed itself when I removed the stroke from that one shape and selected "Preview" in the "View". Not sure what caused it.

I added a 20% grey cmyk stroke to a rectangle and got this error. It was in an EPS file supplied by a customer. I'm using a

27" iMac 2017
4.2 GHz Quad-Core Intel Core i7
Radeon Pro 580 8 GB
64 GB 2400 MHz DDR4

I went to edit > undo, view > preview and it went back to how it was. I created a new rectangle and applied the strroke and no error. originally i was adding the stroke to a rectangle that already existed in the file.

이 문제가 아직도 해결되지 않았나요?
대용량의 인쇄물을 작업할 때 간혹 아웃라인만 남긴 채 미리보기를 로드 할 수 없는
문제를 작년에도 경험했습니다.

해결법은 프로그램을 종료 한 뒤, 상대적으로 저용량의 파일을 먼저 실행 후 대용량의 기존 파일을 여는 것이었습니다. 물론 작업이 지속적으로 진행 될 경우 미리보기를 로드 할 수 없는 문제는 여전했습니다. 게다가 runtime error 까지 뜨는 문제는 해결 될 기미가 전혀 보이지 않습니다.

I had the same problem on a customer-provided file at home. I needed to perform substantial edits to it, and had almost finished, when this happened.
System:
Windows 11 Pro
AMD Ryzen Threadripper Pro 3955wx
128GB 3200MHz DDR4
Nvidia RTX3090ti
4TB Seagate Firecuda 530 RAID10 root drive (4x 2TB)
4TB Seagate Firecuda 530 RAID10 file drive (4x 2TB)
400GB Intel DC 5800x scratch disk
Aside from that, now whenever I mouse over a path in this file, Illustrator freezes for about 10-60 seconds. On the computer I use at work, it would freeze for up to 3 minutes, and it crashed 3 times while trying to select anything at all.
I have tried going back to an earlier (functional) iteration of the file, and this eventually happens again. I tried to create a new file and selectively copy over paths, and this eventually happened again.

I ran into this issue today for the first time. I was working on a file on my iPad and Illustrator stopped registering changes to zoom/pan and I wasn't able to add anything to the document. Tried duplicating the file, tried removing all linked and embedded images, no dice. I opened it on my desktop (2019 Macbook Pro, macOS 11.6.2) and got the "Can't finish previewing" error. Really frustrating, I've been working on this project for weeks!

I updated Illustrator to version 26.1.0, but the problem was not solved. No moderator or administrator of this forum manages to give me an answer. If I create a pdf from Illustrator, then I open it with Acrobat, I can do any enlargement without any kind of problem.

[Ho aggiornato illustrator alla versione 26.1.0, ma il problema non è stato risolto.
Nessun moderatore oppure amministratore di questo forum riesce a darmi una risposta.
Se da illustrator creo un pdf, poi lo apro con Acrobat, posso fare qualsiasi ingrandimento senza alcun tipo di problema.]

Please install the latest version. I solved that problem. Thanks.

Have tried to reboot illustrator many times and reopen my files but it still states can't finish previewing and just shown the outline mode. It crashes when I do my work too
Please help to fix thanks

Goes into Outline view.. Preview mode works when I click the eyeball icon for one of the layers (i.e. turn it off). Using iMac, Big Sur 11.6, AI 26.0.1, 16gb RAM.

This is also happening on the M1 Macs - Enough memory (RAM)

May 2021, I have to stop working for today, AI switches to outline mode with the same error message op described, and other stuff I did today made it crash, I don't know what's going on here but this must be the latest update I installed (version 25.2.3). Very annoying.

Version 25.2.3 And it has not yet been solved. It is impossible to do my work.

I have cc2020, and this still happened.

I applied a pattern to a stroke by accident and received this error. I'm using v25.0.1 on a PC with 16 gb RAM and a dedicated graphics card.

I applied a pattern to a stroke by accident and received this error. I'm using v25.0.1 on a PC with 16 gb RAM and a dedicated graphics card.

I get the "Cannot Finish Previewing. Could Not Complete The Requested Operation" pop-up message and my view goes to Outline Mode when I use the Pencil Tool with a Gradient Fill. I need to save & close the file, reopen it in Outline Mode and then select GPU Preview to see the accurate preview again. Happens every time. I can turn fills off in the Pencil prefs, but that sort of defeats the purpose. Driving me nuts! Please advise.

On mac mini with 64GB w/ a Raedon RX 580 8GB eGPU

Hello from 2020. Not fixed.

I had the same issue on my Apple Macbook Pro (OS Mojave) when using any version of Adobe Illustrator. I went onto Adobe help centre and did an online chat with an agent who logged in remotely to my computer and fixed some files and renamed and deleted a few things, been working ok since.

24.2.2 version crashes automatically. please help

Illustrator crashes while opening other files automatically. Also many times getting can't finish preview while working on linked PDF file only. see attachment, please provide solution.