Getting 400 error when uploading artifacts

Summary

Getting 400 Bad Request when uploading artifact for simple pipeline

Steps to reproduce

create a simple project with only .gitlab-ci.yml that has following lines:

stages:
  - archive
variables:
  ARCH: arch.txt
test:
  stage: archive
  script:
    - echo "This is a test" > $ARCH
    - env >> $ARCH
  artifacts:
    name: archive
    paths:
      - $ARCH

Pipeline finished with following error:

WARNING: Uploading artifacts to coordinator... failed id=512165959 responseStatus=400 Bad Request status=400 Bad Request token=24HE4nqd FATAL: invalid argument
ERROR: Job failed: exit code 1

Example Project

See above. We use gitlab.com

What is the current bug behavior?

(What actually happens)

What is the expected correct behavior?

job artifact is getting uploaded.

Relevant logs and/or screenshots

Running with gitlab-runner 12.9.0 (4c96e5ad)
   on docker-auto-scale fa6cab46
Preparing the "docker+machine" executor
 Using Docker executor with image ruby:2.5 ...
 Pulling docker image ruby:2.5 ...
 Using docker image sha256:813c262b237396b7487c9fb6c97890e6cf9b74dfda43764532dd64f327aa8916 for ruby:2.5 ...
Preparing environment
 Running on runner-fa6cab46-project-18153279-concurrent-0 via runner-fa6cab46-srm-1586960304-f7d09e3a...
Getting source from Git repository
 $ eval "$CI_PRE_CLONE_SCRIPT"
 Fetching changes with git depth set to 50...
 Initialized empty Git repository in /builds/mwaait/infra/misc/artifacts/.git/
 Created fresh repository.
 From https://gitlab.com/mwaait/infra/misc/artifacts
  * [new ref]         refs/pipelines/136263413 -> refs/pipelines/136263413
  * [new branch]      dev                      -> origin/dev
 Checking out cbb7d028 as dev...
 Skipping Git submodules setup
Restoring cache
00:01
Downloading artifacts
00:02
Running before_script and script
 $ echo "This is a test" > $ARCH
 $ env >> $ARCH
Running after_script
00:02
Saving cache
Uploading artifacts for successful job
 Uploading artifacts...
 arch.txt: found 1 matching files                   
 WARNING: Uploading artifacts to coordinator... failed  id=512165959 responseStatus=400 Bad Request status=400 Bad Request token=24HE4nqd
 WARNING: Retrying...                                context=artifacts-uploader error=invalid argument
 WARNING: Uploading artifacts to coordinator... failed  id=512165959 responseStatus=400 Bad Request status=400 Bad Request token=24HE4nqd
 WARNING: Retrying...                                context=artifacts-uploader error=invalid argument
 WARNING: Uploading artifacts to coordinator... failed  id=512165959 responseStatus=400 Bad Request status=400 Bad Request token=24HE4nqd
 FATAL: invalid argument                            
 ERROR: Job failed: exit code 1

Output of checks

This bug happens on GitLab.com

Results of GitLab environment info