After upgrading to Jenkins LTS 2.150.1, it prompted to install basic-branch-build-strategies plugin with a comment that some functionality had moved there (from the core I suppose) and that some of the jobs relied on it. So the plugin was installed.

After that, the GitHub webhooks stopped working. The symptom was that on a push event, either for a new branch or PR, the branch job was created in Jenkins, but the build was not triggered. Combined with required status checks on GitHub, this meant PRs were not mergeable.

The cause was extra configuration with invalid, default values.

Steps to reproduce:

• Create a GitHub organization in Jenkins (with the plugin installed)
• Notice/verify there are no "Build Strategies"
• Install basic-branch-build-strategies 1.1.1
• Now the configuration of the GitHub org has a build strategy:
  • Named Branches
  • Names: Regular Expression: ".*" (dot star)