Fix: Pulumi Stack Locked — Concurrent Update Conflict

!Symptoms

• pulumi up fails with 'the stack is currently locked'
• Cannot run any Pulumi operations on the stack
• Lock was left from a previously cancelled or crashed operation
• CI/CD pipeline stuck waiting for lock release

?Root Causes

• Previous `pulumi up` was cancelled or crashed without releasing the lock
• Another CI/CD pipeline or developer running `pulumi up` concurrently
• Network disconnection during a Pulumi operation left the lock active
• Pulumi backend (S3, GCS, Azure Blob) has stale lock file
• Two branches deploying to the same stack simultaneously

#Diagnosis Steps

1. 1Check who holds the lock: `pulumi stack --show-urls` or check backend directly
2. 2For self-managed backend (S3): check `.pulumi/locks/` in the state bucket
3. 3Check CI/CD pipelines for concurrent runs targeting the same stack
4. 4Check if a team member is running `pulumi up` locally
5. 5Review Pulumi Cloud dashboard for active operations

>Fix

1. 1Cancel the stale lock: `pulumi cancel`
2. 2For self-managed backend: manually delete the lock file from the bucket
3. 3If using Pulumi Cloud: cancel from the web dashboard
4. 4Wait for the concurrent operation to finish if it's legitimate
5. 5Force unlock as last resort — may corrupt state if another operation is truly active

*Prevention

• Use CI/CD concurrency controls to prevent parallel deploys to the same stack
• Set up pipeline locking (GitHub Actions concurrency groups, GitLab resource_group)
• Use short-lived locks with automatic expiration
• Communicate deployments in team chat before running
• Use separate stacks for each developer's feature branches

Related Error Messages