Without having the “content-type: application/json” header set in Postman, I had the same error response about having a missing “data” field (which was actually not true-- the error message simply doesn’t respond correctly if you’re missing the header).
But with the header, it worked.
I checked via the VS Code Extension “HTTP Rest Client” (which is similar to Postman), and it’s the same thing.
So, just make sure the header is set with “content-type: application/json” and you should be good to go.
e.g.: (using VS Code Extension “HTTP Rest Client” )
###
POST http://localhost:1337/api/newsletter-signups
content-type: application/json
{
"data": { "email": "someTest123@test.com" }
}