diff --git a/docs/Gemfile b/docs/Gemfile
index ad16d5073..1d90560bc 100644
--- a/docs/Gemfile
+++ b/docs/Gemfile
@@ -9,7 +9,8 @@ source "https://rubygems.org"
 # This will help ensure the proper Jekyll version is running.
 # Happy Jekylling!
 
-gem "jekyll", "~> 3.8.5"
+gem "jekyll", "~> 4.2.0"
+gem "webrick", "~> 1.7.0"
 gem "minima", "~> 2.0"
 gem 'jekyll-seo-tag'
 
diff --git a/docs/Gemfile.lock b/docs/Gemfile.lock
index e9907f600..27ad53e37 100644
--- a/docs/Gemfile.lock
+++ b/docs/Gemfile.lock
@@ -1,77 +1,83 @@
 GEM
   remote: https://rubygems.org/
   specs:
-    addressable (2.6.0)
-      public_suffix (>= 2.0.2, < 4.0)
+    addressable (2.7.0)
+      public_suffix (>= 2.0.2, < 5.0)
     colorator (1.1.0)
-    concurrent-ruby (1.1.5)
-    em-websocket (0.5.1)
+    concurrent-ruby (1.1.8)
+    em-websocket (0.5.2)
       eventmachine (>= 0.12.9)
       http_parser.rb (~> 0.6.0)
     eventmachine (1.2.7)
-    ffi (1.10.0)
+    ffi (1.15.0)
     forwardable-extended (2.6.0)
     http_parser.rb (0.6.0)
-    i18n (0.9.5)
+    i18n (1.8.9)
       concurrent-ruby (~> 1.0)
-    jekyll (3.8.5)
+    jekyll (4.2.0)
       addressable (~> 2.4)
       colorator (~> 1.0)
       em-websocket (~> 0.5)
-      i18n (~> 0.7)
-      jekyll-sass-converter (~> 1.0)
+      i18n (~> 1.0)
+      jekyll-sass-converter (~> 2.0)
       jekyll-watch (~> 2.0)
-      kramdown (~> 1.14)
+      kramdown (~> 2.3)
+      kramdown-parser-gfm (~> 1.0)
       liquid (~> 4.0)
-      mercenary (~> 0.3.3)
+      mercenary (~> 0.4.0)
       pathutil (~> 0.9)
-      rouge (>= 1.7, < 4)
+      rouge (~> 3.0)
       safe_yaml (~> 1.0)
-    jekyll-feed (0.12.1)
+      terminal-table (~> 2.0)
+    jekyll-feed (0.15.1)
       jekyll (>= 3.7, < 5.0)
-    jekyll-redirect-from (0.15.0)
+    jekyll-redirect-from (0.16.0)
       jekyll (>= 3.3, < 5.0)
-    jekyll-sass-converter (1.5.2)
-      sass (~> 3.4)
-    jekyll-seo-tag (2.6.0)
-      jekyll (~> 3.3)
+    jekyll-sass-converter (2.1.0)
+      sassc (> 2.0.1, < 3.0)
+    jekyll-seo-tag (2.7.1)
+      jekyll (>= 3.8, < 5.0)
     jekyll-watch (2.2.1)
       listen (~> 3.0)
-    kramdown (1.17.0)
+    kramdown (2.3.1)
+      rexml
+    kramdown-parser-gfm (1.1.0)
+      kramdown (~> 2.0)
     liquid (4.0.3)
-    listen (3.1.5)
-      rb-fsevent (~> 0.9, >= 0.9.4)
-      rb-inotify (~> 0.9, >= 0.9.7)
-      ruby_dep (~> 1.2)
-    mercenary (0.3.6)
-    minima (2.5.0)
-      jekyll (~> 3.5)
+    listen (3.5.0)
+      rb-fsevent (~> 0.10, >= 0.10.3)
+      rb-inotify (~> 0.9, >= 0.9.10)
+    mercenary (0.4.0)
+    minima (2.5.1)
+      jekyll (>= 3.5, < 5.0)
       jekyll-feed (~> 0.9)
       jekyll-seo-tag (~> 2.1)
     pathutil (0.16.2)
       forwardable-extended (~> 2.6)
-    public_suffix (3.0.3)
-    rb-fsevent (0.10.3)
-    rb-inotify (0.10.0)
+    public_suffix (4.0.6)
+    rb-fsevent (0.10.4)
+    rb-inotify (0.10.1)
       ffi (~> 1.0)
-    rouge (3.3.0)
-    ruby_dep (1.5.0)
+    rexml (3.2.4)
+    rouge (3.26.0)
     safe_yaml (1.0.5)
-    sass (3.7.4)
-      sass-listen (~> 4.0.0)
-    sass-listen (4.0.0)
-      rb-fsevent (~> 0.9, >= 0.9.4)
-      rb-inotify (~> 0.9, >= 0.9.7)
+    sassc (2.4.0)
+      ffi (~> 1.9)
+    terminal-table (2.0.0)
+      unicode-display_width (~> 1.1, >= 1.1.1)
+    unicode-display_width (1.7.0)
+    webrick (1.7.0)
 
 PLATFORMS
   ruby
 
 DEPENDENCIES
-  jekyll (~> 3.8.5)
+  jekyll (~> 4.2.0)
   jekyll-feed (~> 0.6)
   jekyll-redirect-from
   jekyll-seo-tag
   minima (~> 2.0)
+  webrick (~> 1.7.0)
 
 BUNDLED WITH
-   2.0.1
+   2.2.15
diff --git a/docs/_docs/guide/02-building-open5gs-from-sources.md b/docs/_docs/guide/02-building-open5gs-from-sources.md
index d84acf183..3b3d36914 100644
--- a/docs/_docs/guide/02-building-open5gs-from-sources.md
+++ b/docs/_docs/guide/02-building-open5gs-from-sources.md
@@ -470,6 +470,42 @@ $ sudo ip6tables -t nat -A POSTROUTING -s 2001:230:cafe::/48 ! -o ogstun -j MASQ
 - You can see actual traffic through wireshark -- [[srsenb.pcapng]]({{ site.url }}{{ site.baseurl }}/assets/pcapng/srsenb.pcapng).
 - You can view the log at `$INSTALL_PREFIX/var/log/open5gs/*.log`.
 
+### Re-install with updated source code
+
+You need to update the Open5GS source and all subprojects.
+
+```bash
+$ cd open5gs
+$ git pull ## Update the Open5GS source
+$ meson subprojects update ## Update all subprojects
+```
+
+To compile with meson:
+
+```bash
+$ ninja -C build
+```
+
+Check whether the compilation is correct.
+```bash
+$ cd build
+$ meson test -v
+```
+
+Install Open5GS without making any configuration file changes.
+```bash
+$ ninja install
+```
+
+**Note:** The configuration files in the installation directory are not changed. If you want to initialize the configuration files as well, you need to delete the existing installation directory and install it.
+{: .notice--danger}
+
+Install Open5GS and initialize configuration files.
+```bash
+$ rm -Rf ../install
+$ ninja install
+```
+
 ### Troubleshooting
 ---
 
diff --git a/tests/common/gmm-handler.c b/tests/common/gmm-handler.c
index 36e7cff6e..5c0c558e1 100644
--- a/tests/common/gmm-handler.c
+++ b/tests/common/gmm-handler.c
@@ -55,6 +55,7 @@ void testgmm_handle_registration_accept(test_ue_t *test_ue,
             ogs_nas_parse_nssai(
                     test_ue->allowed_nssai.s_nssai,
                     &registration_accept->allowed_nssai);
+        ogs_assert(test_ue->allowed_nssai.num_of_s_nssai);
     }
     if (registration_accept->presencemask &
         OGS_NAS_5GS_REGISTRATION_ACCEPT_REJECTED_NSSAI_PRESENT) {