routes[0].headers is not a object in vercel.json - vercel

Question

I have been trying to deploy an a Flask API to vercel and I am getting error that routes[0].header should be an object.
I am a beginner and trying to figure this out, any help is appreciated
my vercel.json is
`
{
"version": 2,
"builds": [
{
"src": "./index.py",
"use": "#vercel/python"
}
],
"routes": [
{
"src": "/(.*)",
"dest": "/",
"headers": [
{
"key": "access-control-allow-origin",
"value": "*"
}
]
}
]
}
`
i deployed earlier without headers and it deployed successfully but it was giving me CORS error then i addded the headers and now it is giving me a new error that headers is not a object.
i tried a few different methods but i still can not figure this out

Answer 1

I encountered similar issue and after going through vercel documents https://vercel.com/guides/how-to-enable-cors and few different tries, this worked for me:
The header has to be its own key for specifying access-control-allow-origin and "routes" will need to be replaced with "rewrite" as header and route keys don't go together. And If there are few different domains for your app, you need to duplicate header object within the outer header array for each path for access control origin issue.
Eg:
{
"version": 2,
"builds": [
{
"src": "./index.py",
"use": "#vercel/python"
}
],
"rewrites": [
{ "source": "/(.*)", "destination": "src/app.js" }
],
"headers": [
{
"source": "/(.*)",
"headers": [
{ "key": "Access-Control-Allow-Origin", "value": "*" }
]
},
{
"source": "/vercel_app_domain_name/(.*)",
"headers": [
{ "key": "Access-Control-Allow-Origin", "value": "*" }
]
}
]
}