Getting Error OK as response from http post

Question

I am making an api call to node server. Its a post call but I am getting error as response but the data on firebase changes.

const header : HttpHeaders = new HttpHeaders()
header.append('Content-Type', 'application/x-www-form-urlencoded')

this.http.post('http://localhost:3000/s/getKey', { seqKey : 'invoices' }, {
  headers : header
}).subscribe(data => {
  console.log(data)
})

Update

Answer 1

I had the same problem. I was using the Spring REST API on the backend which was just returning a String, which was a problem because Angular HttpClient expects JSON. I solved it by wrapping my String in a simple POJO and returned that instead.