If you saved the file as an Adobe Cloud Document (prior to the PARM error):

The Adobe Illustrator "Operation cannot complete because of an unknown error. [PARM]" error is a generic alert with multiple potential solutions, ranging from simple preference resets to complex file transfers and language changes. Because it can be triggered by corrupted settings, font conflicts, or cross-region file sharing, a systematic approach is essential.

How to Fix "The operation cannot complete because of an unknown error [PARM]" in Adobe Illustrator

If you see the error while saving, the Adobe Help Center recommends modifying your PDF settings.

This error typically triggers when you try to save a file, export an asset, copy-paste objects, or apply complex vector effects. Because the error points to a vague "parm" (parameter) mismatch within the application code, identifying the root cause requires a systematic troubleshooting approach.

Adobe Illustrator: Operation Cannot Complete Because of an Unknown Error (Parm) — Causes and Fixes

Prevention and best practices