diff --git a/quartz/bootstrap-cli.mjs b/quartz/bootstrap-cli.mjs
index 151a604..99332ba 100755
--- a/quartz/bootstrap-cli.mjs
+++ b/quartz/bootstrap-cli.mjs
@@ -1,4 +1,12 @@
 #!/usr/bin/env -S node --no-deprecation
+const [major] = process.versions.node.split(".").map(Number)
+if (major < 22) {
+  console.error(
+    `\nQuartz requires Node.js >= 22, but you are running Node.js ${process.version}.\n` +
+      `Please upgrade: https://nodejs.org/\n`,
+  )
+  process.exit(1)
+}
 import yargs from "yargs"
 import { hideBin } from "yargs/helpers"
 import {
diff --git a/quartz/cli/handlers.js b/quartz/cli/handlers.js
index 24e9080..084014e 100644
--- a/quartz/cli/handlers.js
+++ b/quartz/cli/handlers.js
@@ -320,6 +320,11 @@ See the [documentation](https://quartz.jzhao.xyz) for how to get started.
  * @param {*} argv arguments for `build`
  */
 export async function handleBuild(argv) {
+  if (argv.concurrency !== undefined && argv.concurrency < 1) {
+    console.error("Concurrency must be at least 1")
+    process.exit(1)
+  }
+
   if (argv.serve) {
     argv.watch = true
   }
@@ -409,7 +414,9 @@ export async function handleBuild(argv) {
     }
 
     const result = await ctx.rebuild().catch((err) => {
-      console.error(`${styleText("red", "Couldn't parse Quartz configuration:")} ${fp}`)
+      console.error(
+        `${styleText("red", "Failed to build Quartz.")} Check for syntax errors in your configuration or plugins.`,
+      )
       console.log(`Reason: ${styleText("gray", err.message ?? String(err))}`)
       process.exit(1)
     })
@@ -545,8 +552,26 @@ export async function handleBuild(argv) {
       return serve()
     })
 
+    server.on("error", (err) => {
+      if (err.code === "EADDRINUSE") {
+        console.error(
+          `Port ${argv.port} is already in use. Try a different port with --port <number>`,
+        )
+        process.exit(1)
+      }
+      throw err
+    })
     server.listen(argv.port)
     const wss = new WebSocketServer({ port: argv.wsPort })
+    wss.on("error", (err) => {
+      if (err.code === "EADDRINUSE") {
+        console.error(
+          `WebSocket port ${argv.wsPort} is already in use. Try a different port with --wsPort <number>`,
+        )
+        process.exit(1)
+      }
+      throw err
+    })
     wss.on("connection", (ws) => connections.push(ws))
     console.log(
       styleText(
@@ -623,7 +648,10 @@ export async function handleUpgrade(argv) {
     }
 
     if (!pullOk) {
-      console.log(styleText("red", "An error occurred above while pulling updates."))
+      console.log(
+        styleText("red", "An error occurred while pulling updates.") +
+          "\nCheck your network connection and git credentials. If you see merge conflicts, resolve them manually and run `npx quartz sync --no-pull`.",
+      )
       await popContentFolder(contentFolder)
       if (fs.existsSync(lockfileBackup)) fs.unlinkSync(lockfileBackup)
       return
@@ -669,7 +697,10 @@ export async function handleUpgrade(argv) {
   if (res.status === 0) {
     console.log(styleText("green", "Dependencies updated!"))
   } else {
-    console.log(styleText("red", "An error occurred above while installing dependencies."))
+    console.log(
+      styleText("red", "An error occurred while installing dependencies.") +
+        "\nTry running `npm install` manually to see detailed errors.",
+    )
   }
 
   console.log("Restoring plugins from lockfile...")
@@ -738,7 +769,10 @@ export async function handleSync(argv) {
     try {
       gitPull(ORIGIN_NAME, QUARTZ_SOURCE_BRANCH)
     } catch {
-      console.log(styleText("red", "An error occurred above while pulling updates."))
+      console.log(
+        styleText("red", "An error occurred while pulling updates from your repository.") +
+          "\nCheck your network connection and git credentials.",
+      )
       await popContentFolder(contentFolder)
       return
     }
@@ -753,7 +787,8 @@ export async function handleSync(argv) {
     })
     if (res.status !== 0) {
       console.log(
-        styleText("red", `An error occurred above while pushing to remote ${ORIGIN_NAME}.`),
+        styleText("red", `An error occurred while pushing to remote ${ORIGIN_NAME}.`) +
+          "\nCheck that you have push access to the remote repository.",
       )
       return
     }