Issue description

Bug Description

The serverless package command fails with exit code 1 when running pnpm install --no-frozen-lockfile, but works perfectly when using the --debug flag. This happens both locally on macOS and in GitHub Actions CI/CD.

Environment Information

Local Environment:

• Framework Version: 4.22.0
• Platform: macOS Darwin 24.6.0 (ARM64_T6000 - Apple Silicon M1)
• Node Version: v20.11.0
• pnpm Version: 10.20.0
• npm Version: 10.2.3

CI Environment:

• Framework Version: 4.19.1
• Platform: Ubuntu 22.04
• Node Version: 20.x
• pnpm Version: 10

Current Behavior

❌ FAILS: Normal execution

$ serverless package
DOTENV: Loading environment variables from .env, .env.local:
	 - evs
Packaging "api" for stage "dev" (us-east-2)

✖ Error: `pnpm install --no-frozen-lockfile` Exited with code 1
    at ChildProcess.<anonymous> (file:///Users/user/.serverless/releases/4.22.0/package/dist/sf-core.js:483:45752)
    at ChildProcess.emit (node:events:530:35)
    at ChildProcess.emit (node:domain:488:12)
    at maybeClose (node:internal/child_process:1105:16)
    at Socket.<anonymous> (node:internal/child_process:457:11)
    at Socket.emit (node:events:518:28)
    at Socket.emit (node:domain:488:12)
    at Pipe.<anonymous> (node:net:337:12)```

### ✅ WORKS: With --debug flag
```bash
$ serverless package --debug
# Works successfully!

✅ WORKS: Manual pnpm install

$ pnpm install --no-frozen-lockfile
Lockfile is up to date, resolution step is skipped
Already up to date
. prepare$ npx husky install
│ husky - install command is DEPRECATED
└─ Done in 1.2s

Steps to Reproduce

1. Have a Serverless v4 project with pnpm-lock.yaml and the configuration below
2. Run serverless package → FAILS
3. Run serverless package --debug → WORKS
4. Run pnpm install --no-frozen-lockfile manually → WORKS

Project Configuration

serverless.yml

service: api

plugins:
  - serverless-dotenv-plugin
  - serverless-offline
  - serverless-prune-plugin

provider:
  name: aws
  runtime: nodejs20.x
  stage: ${opt:stage,'dev'}
  region: us-east-2
  timeout: 10
  environment:
    SERVICE_NAME: ${self:service}
  logRetentionInDays: 30
  architecture: arm64
  memorySize: 1024

package:
  individually: true
  excludeDevDependencies: true
  patterns:
    - "!.git/**"
    - "!**/*.test.*"
    - "!**/__tests__/**"
    - "!**/*.md"
    - "!node_modules/**"
    - "!.env*"

# Split into two separate APIs
resources:
  Resources:
    WebhooksApi:
      Type: AWS::ApiGateway::RestApi
      Properties:
        Name: ${self:provider.stage}-api-webhooks
    MainApi:
      Type: AWS::ApiGateway::RestApi
      Properties:
        Name: ${self:provider.stage}-api

functions:
  - ${file(./handlers/events.yml)}
# ESBuild configuration
build:
  esbuild:
    configFile: ./esbuild.config.js
    buildConcurrency: 3

custom:
  serverless-offline:
    lambdaPort: 4002
    reloadHandler: true
  stage: ${opt:stage, self:provider.stage}
  prune:
    automatic: true # Automatically prune old versions after each deployment
    number: 5 # Keep the 5 most recent versions

esbuild.config.js

module.exports = (serverless) => {
  return {
    bundle: true,
    platform: "node",
    target: "node20",
    external: ["@aws-sdk/*", "@sentry/*", "mongoose", "lambda-log", "pdfkit"],
    minify: true,
    metafile: true,
    buildConcurrency: 3,
    treeShaking: true,
    keepNames: true,
    legalComments: "none",
  }
}

package.json (slightly redacted)

{
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "dev": "chokidar 'handlers' 'src/**/*' 'serverless.yml' 'package.json' --ignore 'src/webhooks/**/*' -c 'pnpm kill-ports && sleep 1 && serverless offline --httpPort 4000 --noTimeout --reloadHandler' --initial --polling",
  },
  "keywords": [],
  "dependencies": {
    "@aws-sdk/client-s3": "^3.864.0",
    "@sendgrid/mail": "^8.1.4",
    "@sentry/aws-serverless": "^10.22.0",
    "@sentry/profiling-node": "^10.22.0",
    "axios": "^1.7.9",
    "cli-progress": "^3.12.0",
    "date-fns": "^4.1.0",
    "date-fns-tz": "^3.2.0",
    "ics": "^3.8.1",
    "jsonwebtoken": "^9.0.2",
    "jwt-decode": "^4.0.0",
    "lambda-log": "^3.1.0",
    "mailparser": "^3.7.2",
    "mongoose": "8.0.1",
    "mongoose-paginate-v2": "^1.7.4",
    "pdfkit": "^0.16.0",
    "qrcode": "^1.5.4",
    "seatsio": "^85.10.0",
    "short-uuid": "^5.2.0",
    "stripe": "^17.5.0",
    "uuid": "^11.0.5"
  },
  "devDependencies": {
    "@eslint/js": "^9.22.0",
    "@sentry/esbuild-plugin": "^4.6.0",
    "@types/jest": "^30.0.0",
    "chokidar-cli": "^3.0.0",
    "esbuild-visualizer": "^0.7.0",
    "eslint": "^9.22.0",
    "globals": "^16.0.0",
    "husky": "^9.1.7",
    "jest": "^30.1.3",
    "lambda-tester": "^4.0.1",
    "mock-jwks": "1.0.10",
    "mongodb-memory-server": "8.16.0",
    "nock": "^13.5.6",
    "serverless-domain-manager": "^8.0.0",
    "serverless-dotenv-plugin": "^6.0.0",
    "serverless-offline": "^14.4.0",
    "serverless-prune-plugin": "^2.1.0",
    "ts-jest": "^29.4.2",
    "tsx": "^4.20.6",
    "typescript": "^5.9.2"
  }
}

Analysis & Observations

1. The --debug flag changes the execution behavior - This suggests the issue is in how Serverless Framework spawns the pnpm child process in normal vs debug mode
2. Manual pnpm install works perfectly - The issue is not with pnpm itself
3. No actual error output from pnpm - The child process fails silently without stderr/stdout
4. Happens on both macOS ARM64 and Ubuntu x64 - Not architecture-specific
5. Using esbuild with custom config - May be related to the build pipeline, however I rolled back to the version before I made the esbuild changes and it still does not work.

Potential Root Causes

• Different stdio handling between debug and normal modes
• Race condition that debug mode avoids by being slower
• Issue with how the child process inherits the parent process environment

Attempted Solutions

• Verified pnpm is installed and in PATH
• Cleared pnpm cache with pnpm store prune
• Deleted and reinstalled node_modules
• Confirmed Node version compatibility

Workarounds

1. Use serverless package --debug (works but verbose)

Expected Behavior

serverless package should work consistently regardless of the --debug flag when pnpm dependencies are already installed.

Additional Context

• Project uses husky git hooks (prepare script)
• Multiple serverless plugins are in use
• Using custom esbuild configuration
• Issue appeared recently without code changes
• Tried to run serverless support --summary and got No previous command information was found even thought I had run the command before and followed instructions