diff --git a/docs/_theme/search.html b/docs/_theme/search.html
index 3174129b1c..8da2bd997a 100644
--- a/docs/_theme/search.html
+++ b/docs/_theme/search.html
@@ -13,6 +13,7 @@
 {%- block scripts %}
     {{ super() }}
     <script type="text/javascript" src="{{ pathto('_static/searchtools.js', 1) }}"></script>
+    <script type="text/javascript" src="{{ pathto('_static/language_data.js', 1) }}"></script>
 {%- endblock %}
 
 {% block footer %}
diff --git a/requirements_docs.txt b/requirements_docs.txt
index c227c0d845..778267ae9c 100644
--- a/requirements_docs.txt
+++ b/requirements_docs.txt
@@ -1,6 +1,6 @@
 docutils>=0.15
 pygments>=2.6
-sphinx>=3.0,!=3.2.0
+sphinx>=4.0, <5.0
 sphinx_rtd_theme>=0.5
 nbsphinx>=0.5
 datatable