--- a/xml/en/docs/http/ngx_http_upstream_module.xml	Tue Sep 24 15:51:59 2019 +0300
+++ b/xml/en/docs/http/ngx_http_upstream_module.xml	Wed Sep 25 16:06:51 2019 +0300
@@ -10,7 +10,7 @@
 <module name="Module ngx_http_upstream_module"
         link="/en/docs/http/ngx_http_upstream_module.html"
         lang="en"
-        rev="80">
+        rev="81">
 
 <section id="summary">
 
@@ -221,6 +221,11 @@
 <tag-desc>
 marks the server as a backup server.
 It will be passed requests when the primary servers are unavailable.
+<note>
+The parameter cannot be used along with the
+<link id="hash"/>, <link id="ip_hash"/>, and <link id="random"/>
+load balancing methods.
+</note>
 </tag-desc>
 
 <tag-name id="down">