Please update your troubleshooting/fix instruction for the bg "The operation cannot complete because of an unknown error. [CANT]".
Effect - > 3D -> Extrude & Bevel...
Following all the Adobe Support site instructions, the bug could not be solved. Even after uninstalled Illustrator and re-installed it, the issue persist.
*MacOS Bug Sur: 2 GHz Quad-Core Intel Core i5 & 16 GB(Memory) 3733 MHz LPDDR4X
*Creative Cloud - Illustrator 2021
Applied all the troubleshooting documented in:
And other similar pages without positive results.