If no fix works:
This fixes about 80% of recurring unknown errors.
The "Unknown Error" often relates to the video card not rendering a specific effect. If no fix works: This fixes about 80%
You attempt to save an existing file or save a new version, and the error pops up at ~50–90% progress.
Sometimes the software's internal settings become "clogged" or corrupted. Resetting them is a standard "factory reset" for the app. If the error occurs on a specific file,
Are you seeing a (like !now or !IMP ) at the end of your error message?
If the error occurs on a specific file, try converting your text to outlines ( Shift + Cmd + O or Shift + Ctrl + O ). If it saves successfully after this, a specific font in your document is likely corrupted. not your artwork.
If the error happens across multiple files or won't go away, the issue is likely with the Illustrator installation, not your artwork.
Illustrator crashes or shows the unknown error immediately after selecting a file.