From 6bc474046ecb4b3ff83c0508d6ee8f27217ae0bc Mon Sep 17 00:00:00 2001
From: Hashim Khan <64767361+Hashim1999164@users.noreply.github.com>
Date: Fri, 11 Sep 2026 02:44:10 +0500
Subject: [PATCH 1/2] Exit when stdout is a broken pipe

Fixes #8458
---
 src/commands/main.ts                     | 13 +++++++
 src/utils/command-helpers.ts             | 27 +++++++++++--
 tests/unit/utils/command-helpers.test.ts | 49 +++++++++++++++++++++++-
 3 files changed, 83 insertions(+), 6 deletions(-)

diff --git a/src/commands/main.ts b/src/commands/main.ts
index 0eef5a1433e..a0df8a017bf 100644
--- a/src/commands/main.ts
+++ b/src/commands/main.ts
@@ -16,6 +16,7 @@ import {
   NETLIFY_CYAN,
   USER_AGENT,
   logError,
+  isBrokenPipe,
 } from '../utils/command-helpers.js'
 import execa from '../utils/execa.js'
 import { EXIT_CODES } from '../utils/exit-codes.js'
@@ -76,9 +77,21 @@ export const CI_FORCED_COMMANDS = {
 
 const SYSTEM_INFO_TIMEOUT = 5_000
 
+const exitIfBrokenPipe = (err: NodeJS.ErrnoException) => {
+  if (isBrokenPipe(err)) {
+    process.exit(0)
+  }
+}
+
+process.stdout.on('error', exitIfBrokenPipe)
+process.stderr.on('error', exitIfBrokenPipe)
+
 let isHandlingUncaughtException = false
 
 process.on('uncaughtException', async (err: AddressInUseError | Error) => {
+  if (isBrokenPipe(err)) {
+    process.exit(0)
+  }
   if (isHandlingUncaughtException) {
     process.exit(1)
   }
diff --git a/src/utils/command-helpers.ts b/src/utils/command-helpers.ts
index 0775c79f230..884b32d7597 100644
--- a/src/utils/command-helpers.ts
+++ b/src/utils/command-helpers.ts
@@ -153,12 +153,31 @@ export const getToken = async (tokenFromOptions?: string): Promise<TokenTuple> =
 // 'functions:invoke' need to return the data from the function as is
 const isDefaultJson = () => argv[0] === 'functions:invoke' || (argv[0] === 'api' && !argv.includes('--list'))
 
+export const isBrokenPipe = (err: unknown): boolean => {
+  if (!err || typeof err !== 'object') {
+    return false
+  }
+  const code = 'code' in err ? err.code : undefined
+  return code === 'EPIPE' || code === 'ERR_STREAM_DESTROYED'
+}
+
+const writeOrExit = (stream: NodeJS.WriteStream, chunk: string) => {
+  try {
+    stream.write(chunk)
+  } catch (err) {
+    if (isBrokenPipe(err)) {
+      process.exit(0)
+    }
+    throw err
+  }
+}
+
 /**
  * logs a json message
  */
 export const logJson = (message: unknown = '') => {
   if (argv.includes('--json') || isDefaultJson()) {
-    process.stdout.write(JSON.stringify(message, null, 2))
+    writeOrExit(process.stdout, JSON.stringify(message, null, 2))
   }
 }
 
@@ -168,7 +187,7 @@ export const log = (message = '', ...args: string[]) => {
     return
   }
   message = typeof message === 'string' ? message : inspect(message)
-  process.stdout.write(`${format(message, ...args)}\n`)
+  writeOrExit(process.stdout, `${format(message, ...args)}\n`)
 }
 
 export const logPadded = (message = '', ...args: string[]) => {
@@ -204,9 +223,9 @@ export const logError = (message: unknown): void => {
 
   const bang = chalk.red(BANG)
   if (process.env.DEBUG) {
-    process.stderr.write(` ${bang}   Warning: ${err.stack?.split('\n').join(`\n ${bang}   `)}\n`)
+    writeOrExit(process.stderr, ` ${bang}   Warning: ${err.stack?.split('\n').join(`\n ${bang}   `)}\n`)
   } else {
-    process.stderr.write(` ${bang}   ${chalk.red(`${err.name}:`)} ${err.message}\n`)
+    writeOrExit(process.stderr, ` ${bang}   ${chalk.red(`${err.name}:`)} ${err.message}\n`)
   }
 }
 
diff --git a/tests/unit/utils/command-helpers.test.ts b/tests/unit/utils/command-helpers.test.ts
index 7e367db8141..9b5c2f4c42c 100644
--- a/tests/unit/utils/command-helpers.test.ts
+++ b/tests/unit/utils/command-helpers.test.ts
@@ -1,6 +1,51 @@
-import { describe, expect, test } from 'vitest'
+import { describe, expect, test, vi } from 'vitest'
+
+import { isBrokenPipe, log, normalizeConfig } from '../../../src/utils/command-helpers.js'
+
+describe('normalizeConfig', () => {
+  test('should remove publish and publishOrigin property if publishOrigin is "default"', () => {
+    const config = { build: { publish: 'a', publishOrigin: 'default' } }
+
+    // @ts-expect-error TS(2345) FIXME: Argument of type '{ build: { publish: string; publ... Remove this comment to see the full error message
+    expect(normalizeConfig(config)).toEqual({ build: {} })
+  })
+
+  test('should return same config object if publishOrigin is not "default"', () => {
+    const config = { build: { publish: 'a', publishOrigin: 'b' } }
+
+    // @ts-expect-error TS(2345) FIXME: Argument of type '{ build: { publish: string; publ... Remove this comment to see the full error message
+    expect(normalizeConfig(config)).toBe(config)
+  })
+})
+
+describe('isBrokenPipe', () => {
+  test('matches EPIPE and destroyed stream codes', () => {
+    expect(isBrokenPipe({ code: 'EPIPE' })).toBe(true)
+    expect(isBrokenPipe({ code: 'ERR_STREAM_DESTROYED' })).toBe(true)
+    expect(isBrokenPipe({ code: 'EIO' })).toBe(false)
+    expect(isBrokenPipe(null)).toBe(false)
+  })
+})
+
+describe('log', () => {
+  test('exits 0 when stdout write throws EPIPE', () => {
+    const write = vi.spyOn(process.stdout, 'write').mockImplementation(() => {
+      const err = new Error('broken pipe') as NodeJS.ErrnoException
+      err.code = 'EPIPE'
+      throw err
+    })
+    const exit = vi.spyOn(process, 'exit').mockImplementation(() => {
+      throw new Error('exited')
+    })
+
+    expect(() => log('hello')).toThrow('exited')
+    expect(exit).toHaveBeenCalledWith(0)
+
+    write.mockRestore()
+    exit.mockRestore()
+  })
+})
 
-import { normalizeConfig } from '../../../src/utils/command-helpers.js'
 
 describe('normalizeConfig', () => {
   test('should remove publish and publishOrigin property if publishOrigin is "default"', () => {

From 74d04b2c20dd8095975ee7cd5ccb29a8dc02edf6 Mon Sep 17 00:00:00 2001
From: Hashim Khan <64767361+Hashim1999164@users.noreply.github.com>
Date: Fri, 11 Sep 2026 04:10:37 +0500
Subject: [PATCH 2/2] Rethrow stream errors that are not a broken pipe.

---
 src/commands/main.ts                     | 1 +
 tests/unit/utils/command-helpers.test.ts | 4 +++-
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/commands/main.ts b/src/commands/main.ts
index a0df8a017bf..05ca69c0fcc 100644
--- a/src/commands/main.ts
+++ b/src/commands/main.ts
@@ -81,6 +81,7 @@ const exitIfBrokenPipe = (err: NodeJS.ErrnoException) => {
   if (isBrokenPipe(err)) {
     process.exit(0)
   }
+  throw err
 }
 
 process.stdout.on('error', exitIfBrokenPipe)
diff --git a/tests/unit/utils/command-helpers.test.ts b/tests/unit/utils/command-helpers.test.ts
index 9b5c2f4c42c..fdc8959cfbf 100644
--- a/tests/unit/utils/command-helpers.test.ts
+++ b/tests/unit/utils/command-helpers.test.ts
@@ -38,7 +38,9 @@ describe('log', () => {
       throw new Error('exited')
     })
 
-    expect(() => log('hello')).toThrow('exited')
+    expect(() => {
+      log('hello')
+    }).toThrow('exited')
     expect(exit).toHaveBeenCalledWith(0)
 
     write.mockRestore()