diff --git a/en_US/howto/upgrade.debian.10-11.md b/en_US/howto/upgrade.debian.10-11.md
index 59877bfa..a754fe22 100644
--- a/en_US/howto/upgrade.debian.10-11.md
+++ b/en_US/howto/upgrade.debian.10-11.md
@@ -25,3 +25,14 @@ Services must be restarted:
 service iredapd restart
 service iredadmin restart
 ```
+
+## php-fpm
+
+Debian 11 ships php 7.4, but Debian 10 ships php 7.3. Although php7.4-fpm
+service is started by default after OS upgrade, but you still need to copy
+old php-fpm config file and restart php7.4-fpm service:
+
+```
+cp /etc/php/7.3/fpm/pool.d/www.conf /etc/php/7.4/fpm/pool.d/www.conf
+service php7.4-fpm restart
+```
diff --git a/html/upgrade.debian.10-11.html b/html/upgrade.debian.10-11.html
index 0c48e360..d630ad4b 100644
--- a/html/upgrade.debian.10-11.html
+++ b/html/upgrade.debian.10-11.html
@@ -21,6 +21,7 @@
 <li><a href="#fixes-you-need-after-upgrading-debian-from-10-to-11">Fixes you need after upgrading Debian from 10 to 11</a><ul>
 <li><a href="#sogo-groupware">SOGo Groupware</a></li>
 <li><a href="#iredapd-and-iredadmin-pro">iRedAPD and iRedAdmin(-Pro)</a></li>
+<li><a href="#php-fpm">php-fpm</a></li>
 </ul>
 </li>
 </ul>
@@ -40,6 +41,14 @@ SOGo at all.</p>
 <p>Services must be restarted:</p>
 <pre><code>service iredapd restart
 service iredadmin restart
+</code></pre>
+
+<h2 id="php-fpm">php-fpm</h2>
+<p>Debian 11 ships php 7.4, but Debian 10 ships php 7.3. Although php7.4-fpm
+service is started by default after OS upgrade, but you still need to copy
+old php-fpm config file and restart php7.4-fpm service:</p>
+<pre><code>cp /etc/php/7.3/fpm/pool.d/www.conf /etc/php/7.4/fpm/pool.d/www.conf
+service php7.4-fpm restart
 </code></pre><div class="footer">
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