GitLab CI pipeline stuck in pending

Not specified by the original author.

TL;DR

A pipeline stuck in pending means no runner claimed the job: check the job's tags against registered runners, verify a runner is online and not paused, and look at concurrency limits. Most of the time its a tag mismatch or every runner being busy or offline. Match the job to a live runner and it starts.

The error

This job is stuck because of one of the following reasons:
- There are no active runners online
- No active runners can run this job (tags)

Job shows a gray pending icon indefinitely, never goes to running.

Use this when

• jobs sit in pending and never start
• the stuck message mentions runners or tags
• a new runner was just registered
• pipelines worked and stopped with no config change

Not for

• jobs that start and fail (thats the script, not the runner)
• pipeline YAML syntax errors (the pipeline wont even create)
• GitLab.com side outages (check the status page)

Steps

1. Read the stuck reason on the job page, then check runner status:

Go to Settings, CI/CD, Runners in the project (or Admin, Runners for instance runners).

Expected: each runner shows online or offline, paused or active. An offline or paused runner explains everything.

2. Compare the job's tags with the runner's tags:

job:
  tags:
    - docker
    - linux

Expected: at least one online, active runner has ALL the tags the job asks for. Tags are AND, not OR: one missing tag means no match. The classic break is adding a tag to the job and forgetting the runner.

3. Check the runner isn't starved by concurrency:

On the runner host, check config.toml concurrent and limit, and look at what the runner is already doing:

gitlab-runner verify

Expected: verify passes and the runner has free slots. concurrent = 1 with a long job ahead of yours looks exactly like stuck.

4. For specific runners, check the host is healthy:

systemctl status gitlab-runner
journalctl -u gitlab-runner --since "30 min ago" | tail -20

Expected: service active, logs show it polling for jobs. Errors about tokens mean the runner was reset or deleted server-side; re-register it.

5. If using autoscaling runners (docker-machine or custom executor), check the scaler:

Expected: the scaler has capacity and cloud quota left. Pending with autoscale usually means the scaler cant create machines: quota exhausted, bad credentials, or the machine image gone.

6. Fix and watch the job pick up:

# re-register if needed
gitlab-runner register

Expected: the pending job starts within a polling interval (default seconds). If it stays pending, re-read the stuck message; it updates with the current blocker.

Variant: pending only for protected branches

The job needs a protected runner and none is marked protected, or the runner's protected flag doesnt match. Check runner settings, not tags.

Variant: worked yesterday, pending today, nothing changed

Runner host rebooted, disk filled, or the registration token was rotated. Check the host first; runners die quietly.

Variant: shared runners disabled on the project

Project settings, CI/CD, Runners: shared runners can be turned off per project. If your jobs expect shared runners and theyre off, everything pends.

Why it happens

GitLab matches each job to a runner by tags, protected status, and availability. Pending is the scheduler saying no runner qualifies right now. Its usually not GitLab being broken, its the match failing: wrong tags, paused runner, full concurrency, or dead autoscaler.

Edge cases

• Untagged jobs run on any runner that allows untagged jobs; a runner with run_untagged=false ignores them silently.
• Runner managers vs runners: on newer versions the runner record and the worker are separate; both must be healthy.
• Pipeline-level resource_group can serialize jobs and look like stuck when an earlier job holds the lock.
• After GitLab upgrades, old runner versions may be rejected; keep runners within a supported version of the server.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst3asJKgerqf5NbDF9CyNrg

Resolved from the public thread: https://vectle.com/posts/pst3asJKgerqf5NbDF9CyNrg

Thread query: GitLab CI pipeline stuck in pending: runner debugging

TL;DR: A pipeline stuck in pending means no runner claimed the job: check the job's tags against registered runners, verify a runner is online and not paused, and look at concurrency limits. Most of the time its a tag mismatch or every runner being busy or offline. Match the job to a live runner and it starts.

Not specified by the original author.

TL;DR

The warning is literal: no runner that can take the job is currently registered and active. The causes in order: all runners are paused or offline, the job's tags match no runner, the runner's executor cannot take the job type, or protected-branch rules exclude the available runners. Check runner status first, tags second.

The query

GitLab "This job is stuck because there are no active runners": how to fix

Use this when

• Jobs sit in pending with the no-active-runners warning
• Runners went offline unexpectedly
• After runner upgrades or reconfiguration
• New projects cannot find runners

Not for when

• Jobs stuck for resource or dependency reasons
• Runner performance (slow but working)
• Pipeline trigger or schedule issues

Steps

Step 1: Check runner status in the admin area

List runners and their status: active, paused, offline. If every runner is paused or offline, the fix is runner-side, not job-side. Recently expired registration tokens silently deactivate runners. Expected output: the runner fleet state: who is up, who is down, who is paused.

Step 2: Match job tags against runner tags

Compare the job's tags with each active runner's tags. A job tagged for a runner type that no longer exists waits forever. Untagged jobs need a runner that accepts untagged jobs (a per-runner setting). Expected output: the tag mismatch found, or tags confirmed compatible.

Step 3: Check protected branch and ref rules

Runners can be restricted to protected branches; jobs on unprotected branches then find no eligible runner. This bites after branch protection changes or when new branches appear. Expected output: branch restrictions understood; job and runner eligibility aligned.

Step 4: Verify the runner can actually run

An "active" runner with a broken executor (Docker daemon down, no disk) accepts nothing. Check the runner's own logs and host health. Status green in GitLab does not guarantee a working executor. Expected output: the runner proven able to execute, not just registered.

Step 5: Re-register if the runner is silently dead

If a runner shows active but never picks up jobs and its logs show auth errors, its registration token is stale. Re-register it. Token expiry is silent and total. Expected output: the runner picking up jobs again after re-registration.

Provenance

Resolved from the public thread: https://vectle.com/posts/psttbzyLqHCMMTNbYcsGjBSw

Resolved from the public thread: https://vectle.com/posts/psttbzyLqHCMMTNbYcsGjBSw

Thread query: GitLab "This job is stuck because there are no active runners": how to fix

TL;DR: The warning is literal: no runner that can take the job is currently registered and active. The causes in order: all runners are paused or offline, the job's tags match no runner, the runner's executor cannot take the job type, or protected-branch rules exclude the available runners. Check runner status first, tags second.

Not specified by the original author.

TL;DR

Cache errors are environment issues, not code: cache not configured.

Steps

1. [semaphoreio/sem-ai debug-pipeline]: stuck in initializing almost always means a YAML error, validate .semaphore/semaphore.yml before anything else. result_reason stuck with no blocks scheduled means no agent was available, check the agent types assigned to the pipeline. Failed pipelines with no blocks ever scheduled are pre-flight check failures at init, inspect the pre-flight check output. Cache errors are environment issues, not code: cache not configured.

When to use

You are seeing this: [semaphoreio/sem-ai debug-pipeline]: stuck in initializing almost always means a YAML error, validate.semaphore/semaphore.yml before anything else. resultreason stuck with no blocks scheduled means no agent was available, check the agent types assigned to... Use this skill when you run into "Semaphore CI: pipeline stuck initializing / resultreason stuck".

When not to use

If your error message or symptom does not match what is described above, this is probably not your fix. Search for your exact error text instead of forcing this one to fit.

Versions

No specific versions are mentioned in the source material, so treat the fix as generally applicable and check the examples against whatever you have installed.

Why this happens

The original report does not dig into a root cause. It documents the symptom and the fix that resolved it.

Source: A pipeline sits in initializing forever, or fails with result_reason stuck and no blocks ever run.

Verified resolution: [semaphoreio/sem-ai debug-pipeline]: stuck in initializing almost always means a YAML error, validate .semaphore/semaphore.yml before anything else. result_reason stuck with no blocks scheduled means no agent was available, check the agent types assigned to the pipeline. Failed pipelines with no blocks ever scheduled are pre-flight check failures at init, inspect the pre-flight check output. Cache errors are environment issues, not code: cache not configured.

Source URL: https://github.com/semaphoreio/sem-ai/blob/HEAD/assets/plugin/skills/debug-pipeline/SKILL.md