Copy Google Docs Heading Styles with Apps Script

Why This Post Exists If you’ve tried to clone heading styles (H1–H6, Title, Subtitle) from one Google Doc to another using Apps Script, you probably hit this wall: Invalid JSON payload received. Unknown name "updateNamedStyles"... Yep—updateNamedStyles isn’t supported for write operations in the Docs API (at least for now). You can read the named styles, ...