Trying to run simple JenkinsFile getting 403 forbidden error - jenkins

Question

I am trying to run a simple JenkinsFile
pipeline {
agent any
stages {
stage('Build') {
steps {
sh 'java -version'
}
}
stage('Test') {
steps {
echo 'Testing..'
}
}
}
}
As you can see there isn't much here. But I am getting a forbidden error even though I configured an account which is the owner of the repository. I posted the error as-it-is just changed the username/repository to my-account/my-repo
> git rev-parse --is-inside-work-tree # timeout=10
Fetching changes from the remote Git repository
> git config remote.origin.url https://github.com/my-account/my-repo.git # timeout=10
Fetching without tags
Fetching upstream changes from https://github.com/my-account/my-repo.git
> git --version # timeout=10
using GIT_ASKPASS to set credentials Pull Request Builder
> git fetch --no-tags --progress https://github.com/my-account/my-repo.git +refs/heads/master:refs/remotes/origin/master
ERROR: Error fetching remote repo 'origin'
hudson.plugins.git.GitException: Failed to fetch from https://github.com/my-account/my-repo.git
at hudson.plugins.git.GitSCM.fetchFrom(GitSCM.java:817)
at hudson.plugins.git.GitSCM.retrieveChanges(GitSCM.java:1084)
at hudson.plugins.git.GitSCM.checkout(GitSCM.java:1115)
at org.jenkinsci.plugins.workflow.steps.scm.SCMStep.checkout(SCMStep.java:109)
at org.jenkinsci.plugins.workflow.steps.scm.SCMStep$StepExecutionImpl.run(SCMStep.java:83)
at org.jenkinsci.plugins.workflow.steps.scm.SCMStep$StepExecutionImpl.run(SCMStep.java:73)
at org.jenkinsci.plugins.workflow.steps.AbstractSynchronousNonBlockingStepExecution$1$1.call(AbstractSynchronousNonBlockingStepExecution.java:47)
at hudson.security.ACL.impersonate(ACL.java:221)
at org.jenkinsci.plugins.workflow.steps.AbstractSynchronousNonBlockingStepExecution$1.run(AbstractSynchronousNonBlockingStepExecution.java:44)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:473)
at java.util.concurrent.FutureTask.run(FutureTask.java:262)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:748)
Caused by: hudson.plugins.git.GitException: Command "git fetch --no-tags --progress https://github.com/my-account/my-repo.git +refs/heads/master:refs/remotes/origin/master" returned status code 128:
stdout:
stderr: error: The requested URL returned error: 403 Forbidden while accessing https://github.com/my-account/my-repo.git/info/refs
fatal: HTTP request failed
at org.jenkinsci.plugins.gitclient.CliGitAPIImpl.launchCommandIn(CliGitAPIImpl.java:1924)
at org.jenkinsci.plugins.gitclient.CliGitAPIImpl.launchCommandWithCredentials(CliGitAPIImpl.java:1643)
at org.jenkinsci.plugins.gitclient.CliGitAPIImpl.access$300(CliGitAPIImpl.java:71)
at org.jenkinsci.plugins.gitclient.CliGitAPIImpl$1.execute(CliGitAPIImpl.java:352)
at hudson.plugins.git.GitSCM.fetchFrom(GitSCM.java:815)
... 13 more

Answer 1

One solution is to switch to SSH when checking out the code.(Easier and always works)
If switching is not an option, then use username/password or better, generate a secret key and use that to access your repo.
Since your using it for Pull Request I'm guessing checkout scm, if this is case by default it will use https- which failed for me using 403, unfortunately the issue lied with my git being an old version 1.7/1.8 not sure exactly. Upgrading it worked like a charm :)
Hope it helps :)