how to fix nextjs prerender error - vercel deployment? - next.js

Question

How do I troubleshoot this problem this deployment issue? I am following this tutorial. My node_modules and .next are ignored and not pushed to github. It works locally but can't seem to deploy. I have supplied both the component code as well as the page it's exported on. Let me know if you can see what I am missing.
https://www.youtube.com/watch?v=V4SVNleMitE
deployment errors
Error occurred prerendering page "/components/BlogPosts". Read more: https://nextjs.org/docs/messages/prerender-error
TypeError: Cannot read property 'fields' of undefined
at BlogPosts (/vercel/path0/.next/server/chunks/130.js:39:12)
at d (/vercel/path0/node_modules/react-dom/cjs/react-dom-server.node.production.min.js:33:498)
at bb (/vercel/path0/node_modules/react-dom/cjs/react-dom-server.node.production.min.js:36:16)
at a.b.render (/vercel/path0/node_modules/react-dom/cjs/react-dom-server.node.production.min.js:42:43)
at a.b.read (/vercel/path0/node_modules/react-dom/cjs/react-dom-server.node.production.min.js:41:83)
at Object.exports.renderToString (/vercel/path0/node_modules/react-dom/cjs/react-dom-server.node.production.min.js:52:138)
at Object.renderPage (/vercel/path0/node_modules/next/dist/server/render.js:673:46)
at Object.defaultGetInitialProps (/vercel/path0/node_modules/next/dist/server/render.js:315:51)
at Function.getInitialProps (/vercel/path0/.next/server/pages/_document.js:645:16)
at Object.loadGetInitialProps (/vercel/path0/node_modules/next/dist/shared/lib/utils.js:69:29)
component blog posts
export default function BlogPosts({post }) {
const {title, information,slug , thumbnail} = post.fields
return (
<div>
<div className='container w-50 h-25 mt-4'>
<Image
className='nav'
src={'https:' + thumbnail.fields.file.url}
width={thumbnail.fields.file.details.image.width}
height={thumbnail.fields.file.details.image.height}
/>
</div>
<div>
<div>
<h4 className=''>{title}</h4>
<Link href={'/contentslug/' + slug}>
<a className='btn btn-primary text-white'>Read more</a>
</Link>
</div>
</div>
</div>
)
}
Pages/Posts
import {createClient} from 'contentful'
import BlogPosts from './components/BlogPosts'
import Nav from './components/Nav'
import Logo from './components/Logo'
export async function getStaticProps() {
const client = createClient({
space: process.env.NEXT_PUBLIC_CONTENTFUL_ID,
accessToken: process.env.NEXT_PUBLIC_CONTENTFUL_TOKEN,
})
const res = await client.getEntries({content_type: 'posts'})
return {
props: {
posts: res.items ,
revalidate: 1
}
}
}
export default function Home({posts}) {
console.log(posts);
return (
<div>
<Logo/>
<Nav/>
<div className="container text-center display-5">
{posts.map(post => (
<BlogPosts key={post.sys.id} post={post}/>
))}
</div>
</div>
)
}

Answer 1

You have fields of undefined. this might be caused because of some strange deploying behavior if you are 100% sure your code works.
How to fix (probably):
Build your project locally. if it works, follow the next step
Comment your code in BlogPosts, inside the exported component. The code must work, so your exported component will be empty but working.
Push this code to Vercel.
Uncommit your code. (done at point 2)
Push again.
P.S. this behavior with API is sometimes caused because of API middleware you reworked.