Apollo Core: TypeError: response.http.headers is not iterable

Package: apollo-server-core@2.9.0 Expected Behavior: Well I’m not sure what to expect.

Actual Behavior: These lines in apollo-server-core are stopping my application from returning payloads to the client.

https://github.com/apollographql/apollo-server/blob/master/packages/apollo-server-core/src/runHttpQuery.ts#L309-L313

I receive the following stacktrace:

"TypeError: response.http.headers is not iterable",
              "    at /Users/<ommited>/Documents/<ommited>/<ommitted>/node_modules/apollo-server-core/src/runHttpQuery.ts:311:49",
              "    at Generator.next (<anonymous>)",
              "    at fulfilled (/Users/<ommited>/Documents/<ommited>/<ommitted>/node_modules/apollo-server-core/dist/runHttpQuery.js:4:58)",
              "    at process._tickCallback (internal/process/next_tick.js:68:7)"

When I comment out those 4 lines of code everything works normally.

I have logged what the headers look like at that point and they are the following: Headers { _headers: {} }

Seems to be some class instance of headers however, the way that the core package tries to iterate over the headers causes a type error to be thrown.

I am using apollo-server-express. Any hints as to why its unable to interface with the headers correctly?

This is the minimum code example needed to reproduce:

const app = express();
import { ApolloServer } from 'apollo-server-express';
const server = new ApolloServer({
  schema: schema,
  formatError: (err) =>{
    console.log(err);
    return err;
  },
  context: async ({ req, res, ...rest }, ...other) => {
    return {
      hi: 5
    }
  },
  introspection: true,
  tracing: false,
  cacheControl: false
});

server.applyMiddleware({ app, path: '/api', cors: corsOptions });
const httpServer = createServer(app);
httpServer.listen(PORT, () => console.log('GraphQL API running at http://localhost:3001/api'));

[sportnak]

To provide a little more clarity, this worked for me by changing my baseUrl from . to ./ (mildly infuriating, but c’est la vie)

[stevenolay]

@duxtinto

Hey, how are you doing. I’m not sure what it could be in your specific case but in my case my baseUrl in my tsconfig was incorrect.

Which was interesting because my project compiled just fine if i went in the node modules folder and commented out the part where it was getting the "response.http.headers " is not iterable from.

But as soon as the base url was corrected… the issue magically disappeared. I know this was the issue because I pair programmed with a buddy of mine and we just kept making minor edits to the tsconfig until we could get something to work. To this day I can still reproduce the error just by changing the baseUrl.

** Shrugs **

Sorry if this isn’t of any help…