Unhandled exception: Unsupported operation: serialization of generic DartType: UnknownType(?) (UnknownType)

Question

I keep getting this error

Unhandled exception: Unsupported operation: serialization of generic DartType: UnknownType(?) (UnknownType)

everytime i try to run my project. I run flutter packages pub run build_runner build and I get pub finished with exit code 78

/// Something was unconfigured or mis-configured. const CONFIG = 78;

This is likely because the.dart_tool/build folder was deleted, or you are submitting generated files to your source repository. [SEVERE] Conflicting outputs were detected and the build is unable to prompt for permission to remove them. These outputs must be removed manually or the build can be run with `--delete-conflicting-outputs

I then proceed to run flutter packages pub run build_runner build --delete-conflicting-outputs and get

[INFO] Succeeded after 49.5s with 14 outputs (227 actions)

and on runnning my app we I get the Dart compiler exited unexpectedly.

Answer 1

solved it by adding a build.yaml configs:

    targets:
  $default:
    builders:
      json_serializable:
        options:
          # Options configure how source code is generated for every
          # `@JsonSerializable`-annotated class in the package.
          #
          # The default value for each is listed.
          any_map: false
          checked: false
          create_factory: true
          create_to_json: true
          disallow_unrecognized_keys: false
          explicit_to_json: false
          field_rename: none
          ignore_unannotated: false
          include_if_null: true
          nullable: true

[INFO] Succeeded after 199ms with 0 outputs (0 actions)