Can't push/delete branch

Summary

Can't push to branch, and can't delete it.

Steps to reproduce

Repo: https://gitlab.com/smartmakers/sm-lora-core branch: develop

What is the current bug behavior?

Prevented me from pushing to branch, and not allows to delete.

What is the expected correct behavior?

Should be possible to delete branch.

Relevant logs and/or screenshots

vovka:sm-lora-core vovka$ git push origin develop 
Counting objects: 1, done.
Writing objects: 100% (1/1), 244 bytes | 0 bytes/s, done.
Total 1 (delta 0), reused 0 (delta 0)
remote: error: cannot lock ref 'refs/heads/develop': Unable to create '/var/opt/gitlab/git-data-file04/repositories/smartmakers/sm-lora-core.git/refs/heads/develop.lock': File exists.
remote: 
remote: Another git process seems to be running in this repository, e.g.
remote: an editor opened by 'git commit'. Please make sure all processes
remote: are terminated then try again. If it still fails, a git process
remote: may have crashed in this repository earlier:
remote: remove the file manually to continue.
To git@gitlab.com:smartmakers/sm-lora-core.git
 ! [remote rejected] develop -> develop (failed to update ref)
error: failed to push some refs to 'git@gitlab.com:smartmakers/sm-lora-core.git

vovka:sm-lora-core vovka$ git push origin --delete develop
remote: error: cannot lock ref 'refs/heads/develop': Unable to create '/var/opt/gitlab/git-data-file04/repositories/smartmakers/sm-lora-core.git/refs/heads/develop.lock': File exists.
remote: 
remote: Another git process seems to be running in this repository, e.g.
remote: an editor opened by 'git commit'. Please make sure all processes
remote: are terminated then try again. If it still fails, a git process
remote: may have crashed in this repository earlier:
remote: remove the file manually to continue.
To git@gitlab.com:smartmakers/sm-lora-core.git
 ! [remote rejected] develop (failed to update ref)
error: failed to push some refs to 'git@gitlab.com:smartmakers/sm-lora-core.git'

Output of checks

This bug happens on GitLab.com

Possible fixes

manually delete '/var/opt/gitlab/git-data-file04/repositories/smartmakers/sm-lora-core.git/refs/heads/develop.lock'