Warning in AI "An unknown shading type was encountered"

[Chetan S]

I am trying to open attached PDF file in AI 2022, while opening this file I am getting warning "An unknown shading type was encountered."

All other apps like Acrobat, InDesign, PhotoShop, Preview opens this file without any issue and gradient color is also proper.

Attached screenshot for reference, in layers gradient color seen is proper where as preview is showing blue color for graident.

Can any suggest why this is happening like this in AI, any AI bug?

[Ton Frederiks]

It was not created in Illustrator (encoded by macOS Version 10.15.7 (Build 19H2) Quartz PDFContext).

Other apps just display the content without trying to edit it.

[Larry G. Schneider]

Preview doesn't use the full spectrum of PDF specifications to display the file. It looks like the gradient is a freeform gradient which becomes non-native art when reopened in AI.

[RajaYogash2015]

Hi Xpertios,  I also had this problem.... are you solve this? pls help me.

[Ton Frederiks]

You cannot solve it. Illustrator is not designed to edit every kind of PDF.

[Larry G. Schneider]

One option might be to select the gradient object and use Rasterize to convert it to an image.