WARNING Configuring `ferry_generator:req_builder` in target `care_giver_app:care_giver_app` but this is not a known Builder

I am implementing graphql in my flutter project using Ferry.However,When I try to rebuild the app and generate the schema file using flutter pub run build_runner build --delete-conflicting-outputs command.I get this error.

[INFO] Generating build script...
[INFO] Generating build script completed, took 465ms

[WARNING] Invalidated precompiled build script due to missing asset graph.
[INFO] Precompiling build script......
[INFO] Precompiling build script... completed, took 827ms

[WARNING] Configuring `ferry_generator:req_builder` in target 
`care_giver_app:care_giver_app` but this is not a known Builder
[SEVERE]
type 'Null' is not a subtype of type 'String' in type cast
pub finished with exit code 78

I'm even using the newest version of each package in pubspec.yaml

  build_runner:
  ferry_generator:
  gql_build:
  gql_code_builder:

below is my build.yaml file

targets:
$default:
builders:
  gql_build|schema_builder:
    enabled: true
    options:
      schema: care_giver_app|lib/data/repositories/graphql/schema/schema.graphql
      type_overrides:
        slipImage:
          name: XFiles
  gql_build|ast_builder:
    enabled: true
  gql_build|data_builder:
    enabled: true
    options:
      schema:  care_giver_app|lib/data/repositories/graphql/schema/schema.graphql
      type_overrides:
        slipImage:
          name: XFile
  gql_build|var_builder:
    enabled: true
    options:
      schema: care_giver_app|lib/data/repositories/graphql/schema/schema.graphql
      type_overrides:
        slipImage:
          name: XFile
  gql_build|serializer_builder:
    enabled: true
    options:
      schema: care_giver_app|lib/data/repositories/graphql/schema/schema.graphql
  ferry_generator|req_builder:
    enabled: true
    options:
      schema: care_giver_app|lib/data/repositories/graphql/schema/schema.graphql
      type_overrides:
        slipImage:
          name: XFile