Cannot use GraphQLSchema from another module or realm

Question

I am building a serverless backend using type-graphql and apollo-server-lambda, but after around third request to graphql endpoint I get an error

Error: Cannot use GraphQLSchema "[object GraphQLSchema]" from another module or realm.

Ensure that there is only one instance of "graphql" in the node_modules
directory. If different versions of "graphql" are the dependencies of other
relied on modules, use "resolutions" to ensure only one version is installed.

I have already downgraded type-graphql because version 1.0.0 requires graphql@^15.3.0 while some other dependencies require graphql <= 14

Here are my dependencies

{
  "dependencies": {
    "@types/graphql": "14.5.0",
    "apollo-server-lambda": "^2.17.0",
    "aws-sdk": "^2.750.0",
    "graphql": "^14.7.0",
    "pg": "^8.3.3",
    "reflect-metadata": "^0.1.13",
    "source-map-support": "^0.5.19",
    "type-graphql": "^0.17.0",
  },
  "devDependencies": {
    "@types/aws-lambda": "^8.10.62",
    "@types/aws-sdk": "^2.7.0",
    "@types/jest": "^26.0.13",
    "@types/node": "^14.10.0",
    "apollo-server-testing": "^2.17.0",
    "serverless": "^2.0.0",
    "serverless-offline": "^6.7.0",
    "serverless-webpack": "^5.3.4",
    "ts-jest": "^26.3.0",
    "ts-loader": "^8.0.3",
    "typescript": "^4.0.2",
    "webpack": "^4.44.1",
    "webpack-node-externals": "^2.5.2"
  },
  "resolutions": {
    "graphql": "^14.7.0",
  },

npm ls graphql result

[email protected]
├─┬ @types/[email protected]
│ └── [email protected]  deduped
└── [email protected] 

and index.ts

import "reflect-metadata"
import { buildSchemaSync } from "type-graphql"
import { HelloResolver } from "./src/resolvers/example"

const schema = buildSchemaSync({
    resolvers: [HelloResolver],
    validate: false,
})

const server = new ApolloServer({
    schema,
    playground: { endpoint: "/dev/graphql" },
})

export const handler = server.createHandler({
        cors: {
            origin: true,
            credentials: true,
        },
    })

Answer 1

I had a similar problem and found an advice in typegraphql FAQ. npm dedupe solved it for me.

Answer 2

I've finally found the solution. I upgraded both apollo-server-lambda to 3.0.0-alpha.3 and reverted type-graphql back to ^1.0.0. I also upgraded the resolution to "graphql": "15.3.0"

also an important step when using type-graphql with lambda is to override the global object (name schema matters) - reference issue

if (!global.schema) {
  global.schema = buildSchemaSync({
    resolvers: [UserResolver],
    validate: false,
  });
}
const schema = global.schema;