diff --git a/spring-web/src/main/java/org/springframework/http/client/reactive/NettyHeadersAdapter.java b/spring-web/src/main/java/org/springframework/http/client/reactive/NettyHeadersAdapter.java
index c0c92750eb..603a3e7380 100644
--- a/spring-web/src/main/java/org/springframework/http/client/reactive/NettyHeadersAdapter.java
+++ b/spring-web/src/main/java/org/springframework/http/client/reactive/NettyHeadersAdapter.java
@@ -56,7 +56,9 @@ class NettyHeadersAdapter implements MultiValueMap<String, String> {
 
 	@Override
 	public void add(String key, @Nullable String value) {
-		this.headers.add(key, value);
+		if (value != null) {
+			this.headers.add(key, value);
+		}
 	}
 
 	@Override
@@ -71,7 +73,9 @@ class NettyHeadersAdapter implements MultiValueMap<String, String> {
 
 	@Override
 	public void set(String key, @Nullable String value) {
-		this.headers.set(key, value);
+		if (value != null) {
+			this.headers.set(key, value);
+		}
 	}
 
 	@Override
diff --git a/spring-web/src/main/java/org/springframework/http/server/reactive/NettyHeadersAdapter.java b/spring-web/src/main/java/org/springframework/http/server/reactive/NettyHeadersAdapter.java
index 4d96585fda..dceddb7fb3 100644
--- a/spring-web/src/main/java/org/springframework/http/server/reactive/NettyHeadersAdapter.java
+++ b/spring-web/src/main/java/org/springframework/http/server/reactive/NettyHeadersAdapter.java
@@ -56,7 +56,9 @@ class NettyHeadersAdapter implements MultiValueMap<String, String> {
 
 	@Override
 	public void add(String key, @Nullable String value) {
-		this.headers.add(key, value);
+		if (value != null) {
+			this.headers.add(key, value);
+		}
 	}
 
 	@Override
@@ -71,7 +73,9 @@ class NettyHeadersAdapter implements MultiValueMap<String, String> {
 
 	@Override
 	public void set(String key, @Nullable String value) {
-		this.headers.set(key, value);
+		if (value != null) {
+			this.headers.set(key, value);
+		}
 	}
 
 	@Override
diff --git a/spring-web/src/test/java/org/springframework/http/server/reactive/HeadersAdaptersTests.java b/spring-web/src/test/java/org/springframework/http/server/reactive/HeadersAdaptersTests.java
index ba0deea017..1b7d34290b 100644
--- a/spring-web/src/test/java/org/springframework/http/server/reactive/HeadersAdaptersTests.java
+++ b/spring-web/src/test/java/org/springframework/http/server/reactive/HeadersAdaptersTests.java
@@ -94,6 +94,14 @@ class HeadersAdaptersTests {
 		assertThat(headers.get("TestHeader").size()).isEqualTo(1);
 	}
 
+	@ParameterizedHeadersTest
+	void nullValuesShouldNotFail(String displayName, MultiValueMap<String, String> headers) {
+		headers.add("TestHeader", null);
+		assertThat(headers.getFirst("TestHeader")).isNull();
+		headers.set("TestHeader", null);
+		assertThat(headers.getFirst("TestHeader")).isNull();
+	}
+
 	@Retention(RetentionPolicy.RUNTIME)
 	@Target(ElementType.METHOD)
 	@ParameterizedTest(name = "[{index}] {0}")