Unexpected <EOF> while using graphql

The issue is because the query you're passing might be empty.

For example:

curl -X POST http://localhost:4000/graphql \ 
-H "Content-Type: application/json" \
-d '{"query": "{ user { id } }"}'

works fine.

But if you make something like:

curl -X POST http://localhost:4000/graphql \
-H "Content-Type: application/json" \
-d '{"query": ""}'

You'll get unexpected < EOF >

Also, check GraphQL end of line issue.

I had comments in the schema.graphql file:

"""
Some comments
"""

I removed the comments and the Unexpected <EOF> error went away.

It's because there's no actual query so you get unexpected EOF (End of File).

Guessing that you're using GraphiQL (because your EOF message says line 30); you need to add a query on the left-hand panel of GraphiQL in the browser. Something which conforms to your RootQuery like:

{
  user(id: "1") {
    id,
    firstName,
    age
  }
}