diff --git a/core/src/main/java/org/apache/struts2/interceptor/httpmethod/HttpMethod.java b/core/src/main/java/org/apache/struts2/interceptor/httpmethod/HttpMethod.java
index 8e9b850997..13d3ec283f 100644
--- a/core/src/main/java/org/apache/struts2/interceptor/httpmethod/HttpMethod.java
+++ b/core/src/main/java/org/apache/struts2/interceptor/httpmethod/HttpMethod.java
@@ -18,6 +18,8 @@
  */
 package org.apache.struts2.interceptor.httpmethod;
 
+import java.util.Locale;
+
 /**
  * Enum represents possible http request types
  *
@@ -36,8 +38,28 @@ public enum HttpMethod {
     CONNECT,
     PATCH;
 
+    /**
+     * Returns the {@link HttpMethod} for the given request method, or {@code null} if it is not
+     * one of the methods this enum knows about.
+     *
+     * <p>Use this for the method of an incoming request. The client chooses that token freely,
+     * so an unrecognised value is ordinary input rather than a programming error, and must not
+     * raise.</p>
+     */
+    public static HttpMethod parseOrNull(String httpRequestMethod) {
+        if (httpRequestMethod == null) {
+            return null;
+        }
+
+        try {
+            return valueOf(httpRequestMethod.toUpperCase(Locale.ROOT));
+        } catch (IllegalArgumentException e) {
+            return null;
+        }
+    }
+
     public static HttpMethod parse(String httpRequestMethod) {
-        return valueOf(httpRequestMethod.toUpperCase());
+        return valueOf(httpRequestMethod.toUpperCase(Locale.ROOT));
     }
 
 }
diff --git a/core/src/main/java/org/apache/struts2/interceptor/httpmethod/HttpMethodInterceptor.java b/core/src/main/java/org/apache/struts2/interceptor/httpmethod/HttpMethodInterceptor.java
index c6dbfc0d3b..08b3614018 100644
--- a/core/src/main/java/org/apache/struts2/interceptor/httpmethod/HttpMethodInterceptor.java
+++ b/core/src/main/java/org/apache/struts2/interceptor/httpmethod/HttpMethodInterceptor.java
@@ -95,7 +95,10 @@ public String intercept(ActionInvocation invocation) throws Exception {
         if (action instanceof HttpMethodAware) {
             LOG.debug("Action: {} implements: {}, setting request method: {}",
                 action, HttpMethodAware.class.getSimpleName(), request.getMethod());
-            ((HttpMethodAware) (action)).setMethod(HttpMethod.parse(request.getMethod()));
+            HttpMethod requestedHttpMethod = HttpMethod.parseOrNull(request.getMethod());
+            if (requestedHttpMethod != null) {
+                ((HttpMethodAware) (action)).setMethod(requestedHttpMethod);
+            }
         }
 
         if (invocation.getProxy().isMethodSpecified()) {
diff --git a/core/src/test/java/org/apache/struts2/interceptor/httpmethod/HttpMethodTest.java b/core/src/test/java/org/apache/struts2/interceptor/httpmethod/HttpMethodTest.java
index c56ef5f7ae..2e624171fe 100644
--- a/core/src/test/java/org/apache/struts2/interceptor/httpmethod/HttpMethodTest.java
+++ b/core/src/test/java/org/apache/struts2/interceptor/httpmethod/HttpMethodTest.java
@@ -22,6 +22,7 @@
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
 
 public class HttpMethodTest {
 
@@ -55,4 +56,58 @@ public void shouldValueOfThrowsException() {
         assertEquals(expected.getClass(), IllegalArgumentException.class);
     }
 
+
+    @Test
+    public void shouldParseUnknownRequestMethod_asNull_notRaise() {
+        // given : a request method this enum does not know about, e.g. a WebDAV verb
+        String httpRequestMethod = "PROPFIND";
+
+        // when
+        HttpMethod httpMethod = HttpMethod.parseOrNull(httpRequestMethod);
+
+        // then
+        assertNull(httpMethod);
+    }
+
+    @Test
+    public void shouldParseKnownRequestMethod_regardlessOfCase() {
+        // given
+        String httpRequestMethod = "get";
+
+        // when
+        HttpMethod httpMethod = HttpMethod.parseOrNull(httpRequestMethod);
+
+        // then
+        assertEquals(HttpMethod.GET, httpMethod);
+    }
+
+    @Test
+    public void shouldParseNullRequestMethod_asNull() {
+        // given
+        String httpRequestMethod = null;
+
+        // when
+        HttpMethod httpMethod = HttpMethod.parseOrNull(httpRequestMethod);
+
+        // then
+        assertNull(httpMethod);
+    }
+
+    @Test
+    public void shouldStillRejectUnknownMethodInConfiguration() {
+        // given : configuration is trusted input, an unknown name there is a real error
+        String configuredMethod = "PROPFIND";
+
+        // when
+        Throwable expected = null;
+        try {
+            HttpMethod.parse(configuredMethod);
+        } catch (IllegalArgumentException e) {
+            expected = e;
+        }
+
+        // then
+        assertNotNull(expected);
+    }
+
 }