Looks to be barfing at https://github.com/jenkinsci/github-branch-source-plugin/blob/master/src/main/java/org/jenkinsci/plugins/github_branch_source/GitHubSCMNavigator.java#L130, fwiw.

We did not get here so it seems like the username of the credentials does not match the GitHub user name. You are supposed to have a username/password credentials item with username set to the GitHub account name, and password set to an access token.

If that is the only problem, this should be downgraded and marked with the diagnostics label to give the user some hint what might be wrong. (Only a hint, since we cannot know whether they meant to type in a user name or an organization name. We might however be able to determine that their credentials do not correspond to an actual user; that could be a form validation warning in the configuration screen.)

Aaaaah, password is an access token, not a password - that's not documented anywhere I could find. Lemme try.

Yup, that did it - rewording JIRA.

In the configuration screen we should try to connect to the GH API using the supplied credentials. If that fails, display a form validation error. If it succeeds, check that the username matches an account; if not, display a warning (this is not necessarily fatal since the repoOwner might have been a valid organization, in which case GH is probably not going to care what the username was).

So, what's this code for?

I thought it was to process exactly that case: using a username as repo owner with unrelated credentials (other user).

Also makes sense to have the help for the credentials say what form the credentials should be in - right now it just says "Credentials used to scan branches and check out sources", which doesn't exactly make it clear that this shouldn't be GitHub username and password but instead GitHub username and access token.

abayer I'll jump here as soon as possible.

amuniz true, that use case should work too.

jglick, amuniz, I know why this happened. I have to improve the form validation (specially, credentials).

As part of this PR (associated to this issue) it has implemented:

1. Improve error handling.
2. Anonymous (none) is a option valid for Scan Credentials.
3. A new Implementation of RateLimitHandler. Used in anonymous connections.

Include these improvements in the changelog

Code changed in jenkins
User: Manuel Recena
Path:
src/main/java/org/jenkinsci/plugins/github_branch_source/GitHubSCMNavigator.java
http://jenkins-ci.org/commit/github-branch-source-plugin/0006bcfaeb7565c1b87362467214d598201bc11d
Log:
JENKINS-31574 Improved validation for Scan Credentials

Code changed in jenkins
User: Manuel Recena
Path:
src/main/java/org/jenkinsci/plugins/github_branch_source/GitHubSCMNavigator.java
http://jenkins-ci.org/commit/github-branch-source-plugin/425820b6032758ca75b9bf29842036a390aa5328
Log:
JENKINS-31574 Scan credentials are verified before to start the scanning process

Code changed in jenkins
User: Manuel Recena
Path:
pom.xml
src/main/java/org/jenkinsci/plugins/github_branch_source/Endpoint.java
http://jenkins-ci.org/commit/github-branch-source-plugin/bd7c1601547625c3a664229552fe0aba5ed593ac
Log:
Merge branch 'master' into JENKINS-31574

Code changed in jenkins
User: Manuel Recena
Path:
src/main/java/org/jenkinsci/plugins/github_branch_source/AbstractGitHubSCMSource.java
src/main/java/org/jenkinsci/plugins/github_branch_source/Connector.java
src/main/java/org/jenkinsci/plugins/github_branch_source/GitHubSCMNavigator.java
src/main/java/org/jenkinsci/plugins/github_branch_source/RateLimitExceededException.java
http://jenkins-ci.org/commit/github-branch-source-plugin/c391fecd90b17055a39be5225e69e48fcdc01624
Log:
JENKINS-31574 A customized RateLimitHandler has been added

Code changed in jenkins
User: Manuel Recena
Path:
src/main/java/org/jenkinsci/plugins/github_branch_source/GitHubSCMNavigator.java
http://jenkins-ci.org/commit/github-branch-source-plugin/b8bdb54e1e7eeaa01941f49703009eb99a3041fe
Log:
JENKINS-31574 Removed catch RateLimitExceededException in an authorized scope

Code changed in jenkins
User: Manuel Recena
Path:
src/main/java/org/jenkinsci/plugins/github_branch_source/Connector.java
http://jenkins-ci.org/commit/github-branch-source-plugin/d9acd2d1320378a674031c6258e54e3c8b9963b8
Log:
JENKINS-31574 @jglick's comment was addressed

Code changed in jenkins
User: Manuel Recena
Path:
src/main/java/org/jenkinsci/plugins/github_branch_source/AbstractGitHubSCMSource.java
src/main/java/org/jenkinsci/plugins/github_branch_source/Connector.java
src/main/java/org/jenkinsci/plugins/github_branch_source/GitHubSCMNavigator.java
src/main/java/org/jenkinsci/plugins/github_branch_source/RateLimitExceededException.java
http://jenkins-ci.org/commit/github-branch-source-plugin/0750599a057f19df0d59a8e0fd8996809aaff847
Log:
Merge pull request #11 from recena/JENKINS-31574

JENKINS-31574 Improved validation for Scan Credentials

Compare: https://github.com/jenkinsci/github-branch-source-plugin/compare/384e7a983e15...0750599a057f

https://github.com/jenkinsci/github-branch-source-plugin/releases/tag/github-branch-source-1.1

Anonymous (none) is a option valid for Scan Credentials.

I'm not sure this is a good idea, because the GitHub API is severely restricted for anon access as to make this almost useless. It failed for me (github.com/daniel-beck) after just 30 branches in seven repos.

It failed for me (github.com/daniel-beck) after just 30 branches in seven repos.

Well, it would be valid when you configure only one repository to be monitored for branches. Not much requests are required for that. But yes, it's quite limited.

danielbeck, in general, my PoV is always closer of allow than forbid or deny. Said that,

1. The UI shows to users: Credentials are recommended
2. The behavior when the rate-limit is reached, IMO is well managed. You can see a detailed console output here.
3. It can be helpful for small GitHub Organizations or GitHub User Accounts.
4. it can be very helpful when you work with Github Enterprise Servers where the number of API requests is not limited.