Flutter build_runner error: BuildForInputLogger missing Logger.onLevelChanged

I’m working on a Flutter project (git-touch-rebrand) and I’m encountering an issue when trying to run:

flutter pub run build_runner build --delete-conflicting-outputs

I consistently get the following error.

Error Output

PS D:\Git-Touch\git-touch-rebrand> flutter pub run build_runner build --delete-conflicting-outputs
Deprecated. Use dart run instead.
Building package executable... (16.8s)
Failed to build build_runner:build_runner:

/C:/Users/hamda/AppData/Local/Pub/Cache/hosted/pub.dev/build_runner_core-7.2.8/lib/src/logging/build_for_input_logger.dart:13:7: Error: The non-abstract class
'BuildForInputLogger' is missing implementations for these members:
  - Logger.onLevelChanged

Try to either
  - provide an implementation,
  - inherit an implementation from a superclass or mixin,
  - mark the class as abstract, or
  - provide a 'noSuchMethod' implementation.

class BuildForInputLogger implements Logger {
      ^^^^^^^^^^^^^^^^^^^

/C:/Users/hamda/AppData/Local/Pub/Cache/hosted/pub.dev/logging-1.2.0/lib/src/logger.dart:162:22:
Context: 'Logger.onLevelChanged' is defined here.
  Stream get onLevelChanged {
                     ^^^^^^^^^^^^^^

Failed to update packages.

Analysis

This indicates an incompatibility between build_runner_core and the logging package.

Specifically:

• BuildForInputLogger (from build_runner_core 7.2.8) implements Logger
• Logger (from logging 1.2.0) includes the getter onLevelChanged
• BuildForInputLogger does not implement this getter

pubspec.yaml

name: git_touch
description: A new Flutter project.

publish_to: "none"
version: 1.13.0+26

environment:
  sdk: ">=2.17.5 <3.0.0"

dependencies:
  flutter:
    sdk: flutter
  flutter_localizations:
    sdk: flutter

  gql_github:
    path: ./packages/gql_github
  gql_gitlab:
    path: ./packages/gql_gitlab
  github_trending:
    path: ./packages/github_trending
  antd_mobile:
    path: ../ant-design-mobile-flutter

  cupertino_icons: ^1.0.5
  ferry: ^0.16.1+2
  ferry_flutter: ^0.9.1+1
  file_icon: ^1.0.0
  filesize: ^2.0.1
  fimber: ^0.6.6
  flutter_highlight: ^0.7.0
  flutter_markdown: ^0.6.12
  flutter_svg: ^1.1.5
  flutter_vector_icons: ^2.0.0
  github: ^9.4.0
  gql: ^0.14.0
  gql_http_link: ^0.4.4+1
  http: ^0.13.5
  intl: ^0.20.2
  json_annotation: ^4.7.0
  launch_review: ^3.0.1
  nanoid: ^1.0.0
  package_info_plus: ^2.0.0
  primer: ^0.1.0
  provider: ^6.0.4
  share_plus: ^5.0.0
  shared_preferences: ^2.0.15
  timeago: ^3.3.0
  tuple: ^2.0.1
  uni_links: ^0.5.1
  universal_io: ^2.0.4
  uri: ^1.0.0
  url_launcher: ^6.1.6
  webview_flutter: ^3.0.4
  sentry_flutter: ^6.12.2
  pub_semver: ^2.1.2
  google_fonts: ^3.0.1
  go_router: ^5.1.0
  from_css_color: ^2.0.0
  maps_launcher: ^2.0.1
  path: ^1.8.2
  freezed_annotation: ^3.1.0

dev_dependencies:
  build_runner: ^2.2.0
  ferry_generator: ^0.12.0+3
  flutter_lints: ^6.0.0
  flutter_test:
    sdk: flutter
  freezed: ^3.2.4
  json_serializable: ^6.5.1

flutter:
  generate: true
  assets:
    - images/

flutter_intl:
  enabled: true

Relevant pubspec.lock Versions

packages:
  build_runner:
    version: "2.4.13"        # pubspec.yaml states ^2.2.0
  build_runner_core:
    version: "7.2.8"

  ferry:
    version: "0.11.2+1"      # pubspec.yaml states ^0.16.1+2
  ferry_generator:
    version: "0.6.1"         # pubspec.yaml states ^0.12.0+3
  ferry_flutter:
    version: "0.6.2"         # pubspec.yaml states ^0.9.1+1

  freezed:
    version: "2.2.0"         # pubspec.yaml states ^3.2.4
  freezed_annotation:
    version: "2.4.2"         # pubspec.yaml states ^3.1.0

  gql:
    version: "0.14.0"
  gql_code_builder:
    version: "0.6.0"

  logging:
    version: "1.2.0"

What I’ve Tried So Far

1. Upgraded intl

   • Resolved an earlier intl dependency conflict.

2. Fixed .arb files

   • Corrected FormatException and pluralization errors in:

     • intl_nb.arb
     • intl_zh.arb
     • intl_en.arb

3. Clean & re-fetch dependencies

   • Ran flutter clean
   • Ran flutter pub get, flutter pub upgrade
   • Running flutter pub upgrade --major-versions introduces new conflicts in deeply nested dependencies (ferry, ferry_generator, gql).

4. Tried dependency_overrides for logging

   • Tested logging: 1.2.0 and logging: 1.0.2

   • Error persists, suggesting:

     • onLevelChanged exists even in older versions, or
     • The issue is deeper than a simple override

   • Removing overrides did not help.

5. Attempted broad major upgrades

   • Resulted in cascading conflicts, such as:

     • freezed >=3.1.0 vs freezed_annotation ^2.2.0
     • ferry_flutter vs ferry_generator (conflicting ferry_exec)
     • ferry_flutter vs ferry
     • ferry_generator requiring gql ^1.0.0 while the project uses gql ^0.14.0

Conclusion / Question

The dependency tree appears fragile and outdated, and I’m unable to find a compatible set of versions that satisfies all constraints—especially around:

• build_runner
• build_runner_core
• logging
• the ferry / gql / freezed ecosystem

What is the recommended approach for resolving complex, intertwined dependency conflicts like this in a Flutter project when:

• flutter pub upgrade --major-versions doesn’t converge
• dependency_overrides doesn’t solve the issue

Are there:

• Known stable combinations of build_runner, build_runner_core, and logging that work with older ferry / gql versions?
• A systematic strategy for untangling and modernizing this kind of dependency mess?

Any guidance would be greatly appreciated 🙏