diff --git a/Reverse-Proxy-Diagnostics-Troubleshooting.md b/Reverse-Proxy-Diagnostics-Troubleshooting.md
index b354b8e..aa2016a 100644
--- a/Reverse-Proxy-Diagnostics-Troubleshooting.md
+++ b/Reverse-Proxy-Diagnostics-Troubleshooting.md
@@ -275,4 +275,14 @@ In case connection from reverse proxy towards _Radicale_ is not working or flapp
 | IPv4+IPv6 | 127.0.0.1 | 127.0.0.1 | ok |
 | IPv4+IPv6 | localhost | 127.0.0.1 | flapping |
 | IPv4+IPv6 | 127.0.0.1 | localhost | ok |
-| IPv4+IPv6 | localhost | localhost | ok |
\ No newline at end of file
+| IPv4+IPv6 | localhost | localhost | ok |
+
+# HTTP 100 "Continue" causing issues
+
+Extend Apache ProxyPass configuration with
+
+```
+		<IfVersion >= 2.4.40>
+		Proxy100Continue Off
+		</IfVersion>
+```
\ No newline at end of file