diff --git a/.github/actions/next-stats-action/Dockerfile b/.github/actions/next-stats-action/Dockerfile
index acdb4b43b92ff..216fad1266413 100644
--- a/.github/actions/next-stats-action/Dockerfile
+++ b/.github/actions/next-stats-action/Dockerfile
@@ -9,7 +9,7 @@ RUN apt install unzip wget curl nano htop screen build-essential pkg-config libs
 
 RUN ln $(which python3) /usr/bin/python
 
-RUN curl -sfLS https://install-node.vercel.app/v18.17.0 | bash -s -- -f
+RUN curl -sfLS https://install-node.vercel.app/v21 | bash -s -- -f
 RUN corepack enable
 
 WORKDIR /next-stats
diff --git a/.github/workflows/build_and_deploy.yml b/.github/workflows/build_and_deploy.yml
index 599ba653c36c1..96df9d6f25432 100644
--- a/.github/workflows/build_and_deploy.yml
+++ b/.github/workflows/build_and_deploy.yml
@@ -8,7 +8,7 @@ on:
 env:
   NAPI_CLI_VERSION: 2.16.2
   TURBO_VERSION: 1.10.9
-  NODE_LTS_VERSION: 20
+  NODE_LTS_VERSION: 21
   CARGO_PROFILE_RELEASE_LTO: 'true'
   TURBO_TEAM: 'vercel'
   TURBO_REMOTE_ONLY: 'true'
diff --git a/.github/workflows/build_and_test.yml b/.github/workflows/build_and_test.yml
index 37b1639ceedf7..09181c4be25d4 100644
--- a/.github/workflows/build_and_test.yml
+++ b/.github/workflows/build_and_test.yml
@@ -9,7 +9,7 @@ on:
 env:
   NAPI_CLI_VERSION: 2.14.7
   TURBO_VERSION: 1.10.9
-  NODE_LTS_VERSION: 20
+  NODE_LTS_VERSION: 21
   TEST_CONCURRENCY: 8
   # disable backtrace for test snapshots
   RUST_BACKTRACE: 0
@@ -146,7 +146,7 @@ jobs:
         group: [1, 2, 3, 4, 5]
     uses: ./.github/workflows/build_reusable.yml
     with:
-      nodeVersion: 18.17.0
+      nodeVersion: 21
       skipForDocsOnly: 'yes'
       afterBuild: RUST_BACKTRACE=0 NEXT_EXTERNAL_TESTS_FILTERS="$(pwd)/test/turbopack-tests-manifest.json" TURBOPACK=1 node run-tests.js --timings -g ${{ matrix.group }}/5 -c ${TEST_CONCURRENCY} --type integration
     secrets: inherit
@@ -211,7 +211,7 @@ jobs:
 
     uses: ./.github/workflows/build_reusable.yml
     with:
-      nodeVersion: 18.17.0
+      nodeVersion: 21
       skipForDocsOnly: 'yes'
       afterBuild: node run-tests.js --timings -g ${{ matrix.group }}/12 -c ${TEST_CONCURRENCY} --type integration
     secrets: inherit
diff --git a/.github/workflows/build_reusable.yml b/.github/workflows/build_reusable.yml
index 849580725961a..3d8a5265fce8c 100644
--- a/.github/workflows/build_reusable.yml
+++ b/.github/workflows/build_reusable.yml
@@ -57,7 +57,7 @@ on:
 env:
   NAPI_CLI_VERSION: 2.14.7
   TURBO_VERSION: 1.10.9
-  NODE_LTS_VERSION: 20
+  NODE_LTS_VERSION: 21
   TEST_CONCURRENCY: 8
   # disable backtrace for test snapshots
   RUST_BACKTRACE: 0
diff --git a/.github/workflows/code_freeze.yml b/.github/workflows/code_freeze.yml
index e7813a5b1868e..08ca48b3b6da9 100644
--- a/.github/workflows/code_freeze.yml
+++ b/.github/workflows/code_freeze.yml
@@ -18,7 +18,7 @@ name: Code Freeze
 env:
   NAPI_CLI_VERSION: 2.14.7
   TURBO_VERSION: 1.10.9
-  NODE_LTS_VERSION: 20
+  NODE_LTS_VERSION: 21
 
 jobs:
   start:
diff --git a/.github/workflows/pull_request_stats.yml b/.github/workflows/pull_request_stats.yml
index c88e5a76ad256..6b249a3b2f250 100644
--- a/.github/workflows/pull_request_stats.yml
+++ b/.github/workflows/pull_request_stats.yml
@@ -7,7 +7,7 @@ name: Generate Pull Request Stats
 env:
   NAPI_CLI_VERSION: 2.14.7
   TURBO_VERSION: 1.10.9
-  NODE_LTS_VERSION: 20
+  NODE_LTS_VERSION: 21
   TEST_CONCURRENCY: 6
 
   TURBO_TEAM: 'vercel'
diff --git a/.github/workflows/test_e2e_deploy.yml b/.github/workflows/test_e2e_deploy.yml
index 8046bfd136d41..f9534507eef62 100644
--- a/.github/workflows/test_e2e_deploy.yml
+++ b/.github/workflows/test_e2e_deploy.yml
@@ -16,7 +16,7 @@ jobs:
       DATADOG_API_KEY: ${{ secrets.DATA_DOG_API_KEY }}
       NAPI_CLI_VERSION: 2.16.2
       TURBO_VERSION: 1.10.9
-      NODE_LTS_VERSION: 20
+      NODE_LTS_VERSION: 21
       CARGO_PROFILE_RELEASE_LTO: 'true'
       TURBO_TEAM: 'vercel'
       TURBO_REMOTE_ONLY: 'true'
diff --git a/.github/workflows/trigger_release.yml b/.github/workflows/trigger_release.yml
index cac8403d282a7..ad871bf530aa4 100644
--- a/.github/workflows/trigger_release.yml
+++ b/.github/workflows/trigger_release.yml
@@ -30,7 +30,7 @@ name: Trigger Release
 env:
   NAPI_CLI_VERSION: 2.14.7
   TURBO_VERSION: 1.10.9
-  NODE_LTS_VERSION: 20
+  NODE_LTS_VERSION: 21
 
 jobs:
   start:
diff --git a/.github/workflows/update_fonts_data.yml b/.github/workflows/update_fonts_data.yml
index c47e205bf75c9..e362d8bb1e178 100644
--- a/.github/workflows/update_fonts_data.yml
+++ b/.github/workflows/update_fonts_data.yml
@@ -8,7 +8,7 @@ on:
   workflow_dispatch:
 
 env:
-  NODE_LTS_VERSION: 20
+  NODE_LTS_VERSION: 21
 
 jobs:
   create-pull-request:
diff --git a/azure-pipelines.yml b/azure-pipelines.yml
index a4a63e68955c0..ae4ed45e476f6 100644
--- a/azure-pipelines.yml
+++ b/azure-pipelines.yml
@@ -34,7 +34,7 @@ pr:
 variables:
   PNPM_CACHE_FOLDER: $(Pipeline.Workspace)/.pnpm-store
   NEXT_TELEMETRY_DISABLED: '1'
-  node_version: ^18.17.0
+  node_version: ^21
 
 stages:
   - stage: Test
diff --git a/test/integration/hydrate-then-render/pages/_app.js b/test/integration/hydrate-then-render/pages/_app.js
index b0deb2787a7ab..7d74384dc0507 100644
--- a/test/integration/hydrate-then-render/pages/_app.js
+++ b/test/integration/hydrate-then-render/pages/_app.js
@@ -1,7 +1,7 @@
 /* eslint-disable camelcase */
 import App from 'next/app'
 
-if (typeof navigator !== 'undefined') {
+if (typeof window !== 'undefined' && typeof navigator !== 'undefined') {
   window.__BEACONS = window.__BEACONS || []
 
   navigator.sendBeacon = async function () {
diff --git a/test/integration/relay-analytics-disabled/pages/index.js b/test/integration/relay-analytics-disabled/pages/index.js
index 46c828a80fd0d..35826ac0120af 100644
--- a/test/integration/relay-analytics-disabled/pages/index.js
+++ b/test/integration/relay-analytics-disabled/pages/index.js
@@ -1,4 +1,4 @@
-if (typeof navigator !== 'undefined') {
+if (typeof window !== 'undefined' && typeof navigator !== 'undefined') {
   window.__BEACONS = window.__BEACONS || []
 
   navigator.sendBeacon = async function () {
diff --git a/test/integration/relay-analytics/pages/index.js b/test/integration/relay-analytics/pages/index.js
index 21839b1f6776e..ad04cd2f36be6 100644
--- a/test/integration/relay-analytics/pages/index.js
+++ b/test/integration/relay-analytics/pages/index.js
@@ -1,4 +1,4 @@
-if (typeof navigator !== 'undefined') {
+if (typeof window !== 'undefined' && typeof navigator !== 'undefined') {
   window.__BEACONS = window.__BEACONS || []
   window.__BEACONS_COUNT = new Map()