I've experienced this problem in a different way. Our jenkins installation (master node) is on a Windows machine. We also have a mac mini running a slave node. There are two installations of git that are configured - one is for "Windows" and the other is for "Mac". We must define which installation of git to use for each job - or the wrong one is used and the git commands fail. We also do SCM polling. With Git plugin 1.5, git polling on the Windows machine works fine. With Git plugin 2.0, it attempts to use the Mac installation of git on Windows to do the polling, and the polling fails.

I agree with Charles' observation. If the plugin cannot find Git, then it cannot perform its work. You can either configure the location of Git for the slave as needed, or configure the slave, or consider adding "jgit" as a Git implementation on your master configuration, then define the job to use jgit rather than command line git.

The JGit implementation is not as full featured as the command line git implementation, so there are use cases which it does not meet. You could attempt it and see if it meets your needs.

If git is not configured in the Jenkins configuration, then the plugin cannot use the git executable and cannot perform any operations.

I am facing this problem. BUT git is properly configured. My system is Master on Linux, one slave is also Linux, and other is Windows. The problem is only related to the Windows Slave. It works nicely, till the problem happens. The only way to fix it is restarting Jenkins. Its a real problem, and affecting my teamwork. People ask me why the build was not triggered, and I then ask them to commit something else, after I quickly reboot Jenkins.

The error I get:

Git Polling Log

Started on Jul 3, 2014 3:10:24 PM
Using strategy: Default
[poll] Last Built Revision: Revision 8ae038f280a0faa58243ec1df7af64d961a951c8 (origin/master)
using GIT_SSH to set credentials
> C:\git\cmd\git.exe ls-remote -h git@gitlab:group/repo.git master
FATAL: hudson.plugins.git.GitException: Error performing command: C:\git\cmd\git.exe ls-remote -h git@gitlab:group/repo.git master
hudson.util.IOException2: hudson.plugins.git.GitException: Error performing command: C:\git\cmd\git.exe ls-remote -h git@gitlab:group/repo.git master
at hudson.plugins.git.GitSCM.compareRemoteRevisionWith(GitSCM.java:459)
at hudson.scm.SCM._compareRemoteRevisionWith(SCM.java:356)
at hudson.scm.SCM.poll(SCM.java:373)
at hudson.model.AbstractProject._poll(AbstractProject.java:1584)
at hudson.model.AbstractProject.poll(AbstractProject.java:1493)
at hudson.triggers.SCMTrigger$Runner.runPolling(SCMTrigger.java:462)
at hudson.triggers.SCMTrigger$Runner.run(SCMTrigger.java:491)
at hudson.util.SequentialExecutionQueue$QueueEntry.run(SequentialExecutionQueue.java:118)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334)
at java.util.concurrent.FutureTask.run(FutureTask.java:166)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1146)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:679)
Caused by: hudson.plugins.git.GitException: Error performing command: C:\git\cmd\git.exe ls-remote -h git@gitlab:group/repo.git master
at org.jenkinsci.plugins.gitclient.CliGitAPIImpl.launchCommandIn(CliGitAPIImpl.java:1332)
at org.jenkinsci.plugins.gitclient.CliGitAPIImpl.launchCommandWithCredentials(CliGitAPIImpl.java:1186)
at org.jenkinsci.plugins.gitclient.CliGitAPIImpl.launchCommandWithCredentials(CliGitAPIImpl.java:1110)
at org.jenkinsci.plugins.gitclient.CliGitAPIImpl.launchCommandWithCredentials(CliGitAPIImpl.java:1101)
at org.jenkinsci.plugins.gitclient.CliGitAPIImpl.getHeadRev(CliGitAPIImpl.java:1788)
at hudson.plugins.git.GitSCM.compareRemoteRevisionWithImpl(GitSCM.java:492)
at hudson.plugins.git.GitSCM.compareRemoteRevisionWith(GitSCM.java:457)
... 13 more
Caused by: java.io.IOException: Cannot run program "C:\git\cmd\git.exe": java.io.IOException: error=2, No such file or directory
at java.lang.ProcessBuilder.start(ProcessBuilder.java:488)
at hudson.Proc$LocalProc.<init>(Proc.java:244)
at hudson.Proc$LocalProc.<init>(Proc.java:216)
at hudson.Launcher$LocalLauncher.launch(Launcher.java:773)
at hudson.Launcher$ProcStarter.start(Launcher.java:353)
at org.jenkinsci.plugins.gitclient.CliGitAPIImpl.launchCommandIn(CliGitAPIImpl.java:1321)
... 19 more
Caused by: java.io.IOException: java.io.IOException: error=2, No such file or directory
at java.lang.UNIXProcess.<init>(UNIXProcess.java:164)
at java.lang.ProcessImpl.start(ProcessImpl.java:81)
at java.lang.ProcessBuilder.start(ProcessBuilder.java:470)
... 24 more
Done. Took 68 ms
No changes

I know, it looks like git.exe is not there. But it is, really is. After restarting Jenkins, this happens (on another repo I was able to see the same error, and not I can push something).

Started on Jul 3, 2014 4:04:40 PM
Polling SCM changes on WINMACHINE
Using strategy: Default
[poll] Last Built Revision: Revision 62e80167e7067ede25727c3cb96885551694c860 (origin/master)
> C:\git\cmd\git.exe rev-parse --is-inside-work-tree
Fetching changes from the remote Git repositories
> C:\git\cmd\git.exe config remote.origin.url git@gitlab:tools/repo.git
Fetching upstream changes from git@gitlab:tools/repo.git
> C:\git\cmd\git.exe --version
using GIT_SSH to set credentials
> C:\git\cmd\git.exe fetch --tags --progress git@gitlab:tools/repo.git +refs/heads/:refs/remotes/origin/
Polling for changes in
Seen branch in repository origin/master
Seen 1 remote branch
> C:\git\cmd\git.exe log --full-history --no-abbrev --format=raw -M -m --raw 62e80167e7067ede25727c3cb96885551694c860..bb82f97faa7e27ba53c600050c8bef66df7fe5d0
Done. Took 18 sec
Changes found

Interesting is that now, right below the date, it says:
"Polling SCM changes on WINMACHINE"
This was not available on previous information...
It cannot be trying to go to the wrong machine... or "no-machine"? Its odd...

And I am using "branches to build" = */master

Lovato

I am reopening it since I am facing this, and the only fix I can do is rebooting Jenkins. Then everything starts to work again, for a while.

Looks like a defect.

Best
Lovato