feat: port in use

src/commands/main.ts

@@ -37,30 +37,43 @@ import { createStatusCommand } from './status/index.js'
 import { createSwitchCommand } from './switch/index.js'
 import { createUnlinkCommand } from './unlink/index.js'
 import { createWatchCommand } from './watch/index.js'
-
+import { AddressInUseError } from './types.js'
 const SUGGESTION_TIMEOUT = 1e4
 
-process.on('uncaughtException', async (err) => {
-  console.log('')
-  error(
-    `${chalk.red(
-      'Netlify CLI has terminated unexpectedly',
-    )}\nThis is a problem with the Netlify CLI, not with your application.\nIf you recently updated the CLI, consider reverting to an older version by running:\n\n${chalk.bold(
-      'npm install -g netlify-cli@VERSION',
-    )}\n\nYou can use any version from ${chalk.underline(
-      'https://ntl.fyi/cli-versions',
-    )}.\n\nPlease report this problem at ${chalk.underline(
-      'https://ntl.fyi/cli-error',
-    )} including the error details below.\n`,
-    { exit: false },
-  )
-
-  const systemInfo = await getSystemInfo()
-
-  console.log(chalk.dim(err.stack || err))
-  console.log(chalk.dim(systemInfo))
-
-  reportError(err, { severity: 'error' })
+process.on('uncaughtException', async (err: AddressInUseError | Error) => {
+  if ('code' in err && err.code === 'EADDRINUSE') {
+    error(
+      `${chalk.red(`Port ${err.port} is already in use`)}\n\n` +
+        `Your serverless functions might be initializing a server\n` +
+        `to listen on specific port without properly closing it.\n\n` +
+        `This behavior is generally not advised\n` +
+        `To resolve this issue, try the following:\n` +
+        `1. If you NEED your serverless function to listen on a specific port,\n` +
+        `use a randomly assigned port as we do not officially support this.\n` +
+        `2. Review your serverless functions for lingering server connections, close them\n` +
+        `3. Check if any other applications are using port ${err.port}\n`,
+      { exit: false },
+    )
+  } else {
+    error(
+      `${chalk.red(
+        'Netlify CLI has terminated unexpectedly',
+      )}\nThis is a problem with the Netlify CLI, not with your application.\nIf you recently updated the CLI, consider reverting to an older version by running:\n\n${chalk.bold(
+        'npm install -g netlify-cli@VERSION',
+      )}\n\nYou can use any version from ${chalk.underline(
+        'https://ntl.fyi/cli-versions',
+      )}.\n\nPlease report this problem at ${chalk.underline(
+        'https://ntl.fyi/cli-error',
+      )} including the error details below.\n`,
+      { exit: false },
+    )
+
+    const systemInfo = await getSystemInfo()
+
+    console.log(chalk.dim(err.stack || err))
+    console.log(chalk.dim(systemInfo))
+    reportError(err, { severity: 'error' })
+  }
 
   process.exit(1)
 })

src/commands/types.d.ts

@@ -73,3 +73,11 @@ export type NetlifyOptions = {
   state: StateConfig
   frameworksAPIPaths: FrameworksAPIPaths
 }
+
+export interface AddressInUseError extends Error {
+  code: 'EADDRINUSE'
+  errno: number
+  syscall: 'listen'
+  address: string
+  port: number
+}