We are getting a lot of these errors:

ERROR: Error fetching remote repo 'origin'
hudson.plugins.git.GitException: Failed to fetch from git@gitlab:xxx/main.git
at hudson.plugins.git.GitSCM.fetchFrom(GitSCM.java:810)
at hudson.plugins.git.GitSCM.retrieveChanges(GitSCM.java:1066)
at hudson.plugins.git.GitSCM.checkout(GitSCM.java:1097)
at hudson.scm.SCM.checkout(SCM.java:485)
at hudson.model.AbstractProject.checkout(AbstractProject.java:1269)
at hudson.model.AbstractBuild$AbstractBuildExecution.defaultCheckout(AbstractBuild.java:607)
at jenkins.scm.SCMCheckoutStrategy.checkout(SCMCheckoutStrategy.java:86)
at hudson.model.AbstractBuild$AbstractBuildExecution.run(AbstractBuild.java:529)
at com.tikal.jenkins.plugins.multijob.MultiJobBuild$MultiJobRunnerImpl.run(MultiJobBuild.java:136)
at hudson.model.Run.execute(Run.java:1738)
at com.tikal.jenkins.plugins.multijob.MultiJobBuild.run(MultiJobBuild.java:73)
at hudson.model.ResourceController.execute(ResourceController.java:98)
at hudson.model.Executor.run(Executor.java:410)
Caused by: hudson.plugins.git.GitException: Command "/home/cruise/tools/hudson.plugins.git.GitTool/git-2.7.1/git -c core.askpass=true fetch --no-tags --progress git@gitlab.xxx.com:xxx/main.git +refs/heads/master:refs/remotes/origin/master" returned status code 128:
stdout:
stderr: error: refs/remotes/origin/xxxx does not point to a valid object!
.....
fatal: pack has 120 unresolved deltas
fatal: index-pack failed

at org.jenkinsci.plugins.gitclient.CliGitAPIImpl.launchCommandIn(CliGitAPIImpl.java:1719)
at org.jenkinsci.plugins.gitclient.CliGitAPIImpl.launchCommandWithCredentials(CliGitAPIImpl.java:1463)
at org.jenkinsci.plugins.gitclient.CliGitAPIImpl.access$300(CliGitAPIImpl.java:63)
at org.jenkinsci.plugins.gitclient.CliGitAPIImpl$1.execute(CliGitAPIImpl.java:314)
at org.jenkinsci.plugins.gitclient.RemoteGitImpl$CommandInvocationHandler$1.call(RemoteGitImpl.java:152)
at org.jenkinsci.plugins.gitclient.RemoteGitImpl$CommandInvocationHandler$1.call(RemoteGitImpl.java:145)
at hudson.remoting.UserRequest.perform(UserRequest.java:120)
at hudson.remoting.UserRequest.perform(UserRequest.java:48)
at hudson.remoting.Request$2.run(Request.java:332)
at hudson.remoting.InterceptingExecutorService$1.call(InterceptingExecutorService.java:68)
at java.util.concurrent.FutureTask.run(FutureTask.java:262)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at hudson.remoting.Engine$1$1.run(Engine.java:85)
at java.lang.Thread.run(Thread.java:745)
at ......remote call to build133(Native Method)
at hudson.remoting.Channel.attachCallSiteStackTrace(Channel.java:1416)
at hudson.remoting.UserResponse.retrieve(UserRequest.java:220)
at hudson.remoting.Channel.call(Channel.java:781)
at org.jenkinsci.plugins.gitclient.RemoteGitImpl$CommandInvocationHandler.execute(RemoteGitImpl.java:145)
at sun.reflect.GeneratedMethodAccessor267.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.jenkinsci.plugins.gitclient.RemoteGitImpl$CommandInvocationHandler.invoke(RemoteGitImpl.java:131)
at com.sun.proxy.$Proxy47.execute(Unknown Source)
at hudson.plugins.git.GitSCM.fetchFrom(GitSCM.java:808)
... 12 more
ERROR: null

So I set the Refspec to +refs/heads/master:refs/remotes/origin/master
But when it does a fresh checkout (clean workspace), the plugin does this:

Notice: +refs/heads/:refs/remotes/origin/

Cloning the remote Git repository
Avoid fetching tags
Cloning repository git@gitlab.cj.com:cjdev/main.git
> /home/cruise/tools/hudson.plugins.git.GitTool/git-2.7.1/git init /home/cruise/workspace/Start # timeout=10
Fetching upstream changes from git@gitlab.cj.com:cjdev/main.git
> /home/cruise/tools/hudson.plugins.git.GitTool/git-2.7.1/git --version # timeout=10
using GIT_SSH to set credentials
> /home/cruise/tools/hudson.plugins.git.GitTool/git-2.7.1/git -c core.askpass=true fetch --no-tags --progress git@gitlab.cj.com:cjdev/main.git +refs/heads/:refs/remotes/origin/
> /home/cruise/tools/hudson.plugins.git.GitTool/git-2.7.1/git config remote.origin.url git@gitlab.cj.com:cjdev/main.git # timeout=10
> /home/cruise/tools/hudson.plugins.git.GitTool/git-2.7.1/git config --add remote.origin.fetch +refs/heads/:refs/remotes/origin/ # timeout=10
> /home/cruise/tools/hudson.plugins.git.GitTool/git-2.7.1/git config remote.origin.url git@gitlab.cj.com:cjdev/main.git # timeout=10
Fetching upstream changes from git@gitlab.cj.com:cjdev/main.git
using GIT_SSH to set credentials
> /home/cruise/tools/hudson.plugins.git.GitTool/git-2.7.1/git -c core.askpass=true fetch --no-tags --progress git@gitlab.cj.com:cjdev/main.git +refs/heads/master:refs/remotes/origin/master
> /home/cruise/tools/hudson.plugins.git.GitTool/git-2.7.1/git rev-parse refs/remotes/origin/master^

{commit} # timeout=10
> /home/cruise/tools/hudson.plugins.git.GitTool/git-2.7.1/git rev-parse refs/remotes/origin/refs/heads/master^{commit}

# timeout=10
Checking out Revision b1232ff60185766b8b94dabcc20f147e25ae9aab (refs/remotes/origin/master)
> /home/cruise/tools/hudson.plugins.git.GitTool/git-2.7.1/git config core.sparsecheckout # timeout=10
> /home/cruise/tools/hudson.plugins.git.GitTool/git-2.7.1/git checkout -f b1232ff60185766b8b94dabcc20f147e25ae9aab
> /home/cruise/tools/hudson.plugins.git.GitTool/git-2.7.1/git rev-list 96dd700f85eb3dc07319d302e930053774c86bfc # timeout=10

which I think is what is causing the error when anything from the origin disappears.

Using latest of git plugin, and shared library plugin.