Heroku create-react-app deploy Uncaught SyntaxError: Unexpected token <

Question

Whenever I deploy my heroku app with the create-react-app buildpack, the first time I try to access my domain, the page loaded is white and there is an error in the developer console saying

Uncaught SyntaxError: Unexpected token <

in the file main.6396d38a.js:1 which is generated by the react build. However, when I refresh the page, the website works perfectly fine. Is there a reason this could be happening? I tried to replicate the error on my localhost using npm run build, and serve -s build but my website works perfectly fine there. Why would this only show up once after every react deploy to heroku?

My package.json has a homepage associated with the domain name of my website (not .herokuapp.com)

"homepage": "https://www.example.com/"

Could this be cache issue or potentially it's loading additional chunk? — Riddell
– Riddell, Commented Sep 2, 2019 at 20:47
I don't think it's a cache issue because I can replicate the error across different browsers. What do you mean by an additional chunk? — rmrf
– rmrf, Commented Sep 2, 2019 at 20:47

Riddell · Accepted Answer · 2019-09-02 21:36:31Z

6

Inside your package.json make sure your homepage URL is correct:

"homepage": "https://app.herokuapp.com/"

Update

Further investigation shows this was a caching issue. Clearing cookies, website content, and DNS fixed the issue.

edited Sep 2, 2019 at 21:36

answered Sep 2, 2019 at 20:51

Riddell

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10 Comments

Riddell Over a year ago

@JohnDoe Have you tried the type="text/babel" on script tag trick?

rmrf Over a year ago

It's in the question - on line 1 of main.6396d38a.js

Riddell Over a year ago

Yes I mean the line of code. Quick question. What version react-scripts are you using and is it using babel or JSTransform? Do you use JSX?

rmrf Over a year ago

The files are minified in the build, so the line of code isn't really significant. I am using version 3.1.0 of react-scripts-ts and it is using babel.

Riddell Over a year ago

Are you using TSX ?

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