diff --git a/server/src/main/java/org/opensearch/rest/RestController.java b/server/src/main/java/org/opensearch/rest/RestController.java
index cc9a65dc5ce89..78bebcb9a0af1 100644
--- a/server/src/main/java/org/opensearch/rest/RestController.java
+++ b/server/src/main/java/org/opensearch/rest/RestController.java
@@ -450,7 +450,7 @@ private void handleUnsupportedHttpMethod(
             } else {
                 // Not using the error message directly from 'exception.getMessage()' to avoid unescaped HTML special characters,
                 // in case false-positive cross site scripting vulnerability is detected by common security scanners.
-                msg.append("Unexpected http method");
+                msg.append("Unexpected HTTP method");
             }
             if (validMethodSet.isEmpty() == false) {
                 msg.append(", allowed: ").append(validMethodSet);