GitHub Actions / GitHub Actions

Self-hosted Worker hangs holding runner slot after CompleteJobAsync hits 'workflow instance not found'

Fix GitHub Actions self-hosted runner permanently hanging after CompleteJobAsync fails, consuming runner slots and blocking queued jobs across repositories Includes evidence for GitHub Actions troubleshooting demand.

Source-backed Last updated May 18, 2026 1 source Needs local verification

Category: GitHub Actions
Error signature: CompleteJobAsync hits workflow instance not found worker hangs runner slot blocked
Quick fix: Compare the failing environment with a known working setup, then change one configuration value at a time.
Updated: May 18, 2026
Verification status: Source-backed
Evidence: 1 public source URL

Before you change production

This page includes public source URLs in the imported troubleshooting record. Compare those references with your version and environment before applying changes.

Reproduce the smallest failing action and save non-secret logs before changing configuration.
Check versions for GitHub Actions, related SDKs, package managers, CI runners, and hosting providers.
Change one setting or dependency at a time, then rerun the same failing command or request.
Avoid destructive commands, credential rotation, billing changes, or security relaxations without a rollback plan.

What this error means

CompleteJobAsync hits workflow instance not found worker hangs runner slot blocked is a GitHub Actions failure pattern reported for developers trying to fix github actions self-hosted runner permanently hanging after completejobasync fails, consuming runner slots and blocking queued jobs across repositories. Based on the imported evidence, treat this as a tool-specific troubleshooting page rather than a generic API error.

Why this happens

GitHub Issue #4418 opened by lbgraham on May 14, 2026. Worker acquires job slot but never releases it, causing cascading queue delays. Labels 'bug' in official actions/runner repo. Maps to 'GitHub Actions' category.

Common causes

GitHub Issue #4418 opened by lbgraham on May 14, 2026. Worker acquires job slot but never releases it, causing cascading queue delays. Labels 'bug' in official actions/runner repo. Maps to 'GitHub Actions' category.

Quick fixes

Confirm the exact error signature matches CompleteJobAsync hits workflow instance not found worker hangs runner slot blocked.
Check the GitHub Actions account, local tool state, and provider configuration involved in the failing workflow.
Compare the failing environment with a known working setup, then change one configuration value at a time.

Platform/tool-specific checks

Verify the command, editor, extension, or API client that produced the error.
Compare local settings with CI, deployment, or editor-level settings when the error appears in only one environment.
Avoid deleting credentials, local model data, or project settings until the failing scope is clear.

Step-by-step troubleshooting

Capture the exact error message and the command, editor action, or request that triggered it.
Check whether the failure is account/auth, quota/rate, model/provider, local runtime, or deployment configuration.
Review the source evidence below and compare it with your environment.
Apply one change at a time and rerun the smallest failing action.
Keep the working fix documented for the team or deployment environment.

How to prevent it

Keep provider/tool configuration documented.
Record non-secret diagnostics such as tool version, provider name, model name, and command path.
Add a lightweight check before CI or production workflows depend on the tool.

Diagnostic flow for this page

Match CompleteJobAsync hits workflow instance not found worker hangs runner slot blocked exactly before applying the quick fix.
Compare the failing environment with GitHub Actions versions, account scope, provider settings, and deployment context.
Check the listed common causes in order, starting with the cause that best matches your logs.
Use the evidence status below to decide whether to confirm against public sources or official documentation.
Apply one reversible change, rerun the smallest failing action, and keep rollback notes.

FAQ

What does CompleteJobAsync hits workflow instance not found worker hangs runner slot blocked mean in GitHub Actions?

CompleteJobAsync hits workflow instance not found worker hangs runner slot blocked indicates the workflow described by "Self-hosted Worker hangs holding runner slot after CompleteJobAsync hits 'workflow instance not found'" failed in a GitHub Actions context. Start by confirming the exact signature and the component that emitted it.

What should I check first for CompleteJobAsync hits workflow instance not found worker hangs runner slot blocked?

Check whether this cause matches your environment: GitHub Issue #4418 opened by lbgraham on May 14, 2026. Worker acquires job slot but never releases it, causing cascading queue delays. Labels 'bug' in official actions/runner repo. Maps to 'GitHub Actions' category.

Is the CompleteJobAsync hits workflow instance not found worker hangs runner slot blocked guidance source-backed?

The "Self-hosted Worker hangs holding runner slot after CompleteJobAsync hits 'workflow instance not found'" page is labeled source-backed. It has 1 public source URL from github.com, so use that evidence status when deciding how much additional verification you need.

When should I avoid the quick fix for CompleteJobAsync hits workflow instance not found worker hangs runner slot blocked?

For "Self-hosted Worker hangs holding runner slot after CompleteJobAsync hits 'workflow instance not found'", avoid applying "Compare the failing environment with a known working setup, then change one configuration value at a time." when the error text differs, the affected version or provider is different, or the change would touch credentials, billing, DNS, production deploy settings, or irreversible data.

What should I collect before debugging CompleteJobAsync hits workflow instance not found worker hangs runner slot blocked?

For "Self-hosted Worker hangs holding runner slot after CompleteJobAsync hits 'workflow instance not found'", collect the failing GitHub Actions command or request, non-secret configuration, versions, timestamps, request IDs when available, and the smallest reproduction that still triggers the signature.