error in basic ci implementation in gitlab fatal: couldn't find remote ref

Question

I setup fresh gitlab docker , then set up a runner docker with docer executer based on microsoft/dotnet:latest then I added simple project to gitlab just a dotnet core hello world then I create a ci file as below:

image:  microsoft/dotnet:latest

stages:
  - build


variables:
  project: "ConsoleApp"

before_script:
  - "dotnet restore"

build:
  stage: build
  variables:
    build_path: "$ConsoleApp"
  script:
    - "cd $build_path"
    - "dotnet build"

then in pipleline I get this output:

Preparing environment
 Running on runner-vtysysr-project-2-concurrent-0 via e189cc9d1c60...
Getting source from Git repository
00:07
 Fetching changes with git depth set to 50...
 Reinitialized existing Git repository in /builds/root/gitlabcitest/.git/
 fatal: couldn't find remote ref refs/pipelines/18
Uploading artifacts for failed job
00:06
 ERROR: Job failed: exit code 1

I searched error but all asnwers are about projects which have branches, but I dont have any branch, just a simple hello world project.

Answer 1

The OP ali-kamrani adds in the comments:

my issue was in ssh config in runner docker: after adding the ssh key to docker, the issue is solved.

---

Other avenues (for other users) if this is similar to gitlab-org/gitlab issue 36123

We were using git push --mirror to mirror some projects from a different repository regularly.
As it turns out, it also deletes unknown branches, i.e. pipelines/XXXX and merge/XXXX.

We are now pushing & deleting every branch explicitly and ignoring all pipelines/XXXX and merge/XXXX ones.
Afterwards the error didn't occur again.

I understand you don't have many branches, but the issue here is not with your local branches.
It is with a push operation, initiated locally, pruning remote branches which does not exist locally.

Basically, pipelines are depending on a pipeline specific ref refs/pipelines/* and it has to exist when the pipeline is running.
So if git push --mirror deletes these refs, you might encounter the job failure.

The same issue illustrates a similar scenario:

In our setup, we are using a system hook to mirror our GitLab repositories into another location closer to where our GitLab Runner instances are.
This has worked fine for a long time.

However, now that GitLab is dependent on the refs/pipelines/<pipeline ID> ref existing, all of our runners fail.

The problem is that the refs/pipelines/<pipeline ID> ref gets created behind the scenes and there is no system hook that gets invoked (so we don't know about the new ref that needs to be mirrored).
The built-in Repository Mirroring feature isn't very suitable for us because it must be configured for each repository; with System Hooks, we can automatically mirror all of our repositories.