react 16: Uncaught (in promise) Error: Unexpected token u in JSON at position 0 at A

Question

Had this error appear in my app, so I just started a brand new React16 app with npx create-react-app temp, fired it off with npm start, opened devtools and I get the above message.

It's pointing to line 884 of contentscript.js

Not sure how to cure it so does anyone have any ideas?

I've replicated this on Ubuntu Mate and Linux Mint.

Ubuntu Mate 19.10/8GB/Chrome version 83.0.4103.97 (Official Build) (64-bit) node v14.4.0 npm v6.14.5

Linux Mint 19.3 Tricia/4GB/Chrome version 83.0.4103.97 (Official Build) (64-bit) node v8.10.0 npm v3.5.2

Answer 1

It could be a problem with a Chrome extension. For me, the error went away when I turned off the extension "Shortkeys (Custom Keyboard Shortcuts)".