diff --git a/spring-webflux/src/main/java/org/springframework/web/reactive/resource/VersionResourceResolver.java b/spring-webflux/src/main/java/org/springframework/web/reactive/resource/VersionResourceResolver.java
index 92ed2c4467..ff712f7068 100644
--- a/spring-webflux/src/main/java/org/springframework/web/reactive/resource/VersionResourceResolver.java
+++ b/spring-webflux/src/main/java/org/springframework/web/reactive/resource/VersionResourceResolver.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -317,7 +317,7 @@ public class VersionResourceResolver extends AbstractResourceResolver {
 		public HttpHeaders getResponseHeaders() {
 			HttpHeaders headers = (this.original instanceof HttpResource ?
 					((HttpResource) this.original).getResponseHeaders() : new HttpHeaders());
-			headers.setETag("\"" + this.version + "\"");
+			headers.setETag("W/\"" + this.version + "\"");
 			return headers;
 		}
 	}
diff --git a/spring-webflux/src/test/java/org/springframework/web/reactive/resource/ResourceWebHandlerTests.java b/spring-webflux/src/test/java/org/springframework/web/reactive/resource/ResourceWebHandlerTests.java
index 7bdbeff945..ac96e74ae3 100644
--- a/spring-webflux/src/test/java/org/springframework/web/reactive/resource/ResourceWebHandlerTests.java
+++ b/spring-webflux/src/test/java/org/springframework/web/reactive/resource/ResourceWebHandlerTests.java
@@ -165,7 +165,7 @@ public class ResourceWebHandlerTests {
 		setPathWithinHandlerMapping(exchange, "versionString/foo.css");
 		this.handler.handle(exchange).block(TIMEOUT);
 
-		assertThat(exchange.getResponse().getHeaders().getETag()).isEqualTo("\"versionString\"");
+		assertThat(exchange.getResponse().getHeaders().getETag()).isEqualTo("W/\"versionString\"");
 		assertThat(exchange.getResponse().getHeaders().getFirst("Accept-Ranges")).isEqualTo("bytes");
 		assertThat(exchange.getResponse().getHeaders().get("Accept-Ranges").size()).isEqualTo(1);
 	}
diff --git a/spring-webflux/src/test/java/org/springframework/web/reactive/resource/VersionResourceResolverTests.java b/spring-webflux/src/test/java/org/springframework/web/reactive/resource/VersionResourceResolverTests.java
index 4467fa42fd..e92a0261ed 100644
--- a/spring-webflux/src/test/java/org/springframework/web/reactive/resource/VersionResourceResolverTests.java
+++ b/spring-webflux/src/test/java/org/springframework/web/reactive/resource/VersionResourceResolverTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -175,7 +175,7 @@ public class VersionResourceResolverTests {
 		assertThat(actual.getFilename()).isEqualTo(expected.getFilename());
 		verify(this.versionStrategy, times(1)).getResourceVersion(expected);
 		assertThat(actual).isInstanceOf(HttpResource.class);
-		assertThat(((HttpResource) actual).getResponseHeaders().getETag()).isEqualTo(("\"" + version + "\""));
+		assertThat(((HttpResource) actual).getResponseHeaders().getETag()).isEqualTo(("W/\"" + version + "\""));
 	}
 
 	@Test
diff --git a/spring-webmvc/src/main/java/org/springframework/web/servlet/resource/VersionResourceResolver.java b/spring-webmvc/src/main/java/org/springframework/web/servlet/resource/VersionResourceResolver.java
index 1e089ca01d..d2041e5b65 100644
--- a/spring-webmvc/src/main/java/org/springframework/web/servlet/resource/VersionResourceResolver.java
+++ b/spring-webmvc/src/main/java/org/springframework/web/servlet/resource/VersionResourceResolver.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -313,7 +313,7 @@ public class VersionResourceResolver extends AbstractResourceResolver {
 		public HttpHeaders getResponseHeaders() {
 			HttpHeaders headers = (this.original instanceof HttpResource ?
 					((HttpResource) this.original).getResponseHeaders() : new HttpHeaders());
-			headers.setETag("\"" + this.version + "\"");
+			headers.setETag("W/\"" + this.version + "\"");
 			return headers;
 		}
 	}
diff --git a/spring-webmvc/src/test/java/org/springframework/web/servlet/resource/ResourceHttpRequestHandlerTests.java b/spring-webmvc/src/test/java/org/springframework/web/servlet/resource/ResourceHttpRequestHandlerTests.java
index 9af18827f9..cf00f1bf42 100644
--- a/spring-webmvc/src/test/java/org/springframework/web/servlet/resource/ResourceHttpRequestHandlerTests.java
+++ b/spring-webmvc/src/test/java/org/springframework/web/servlet/resource/ResourceHttpRequestHandlerTests.java
@@ -152,7 +152,7 @@ public class ResourceHttpRequestHandlerTests {
 		this.request.setAttribute(HandlerMapping.PATH_WITHIN_HANDLER_MAPPING_ATTRIBUTE, "versionString/foo.css");
 		this.handler.handleRequest(this.request, this.response);
 
-		assertThat(this.response.getHeader("ETag")).isEqualTo("\"versionString\"");
+		assertThat(this.response.getHeader("ETag")).isEqualTo("W/\"versionString\"");
 		assertThat(this.response.getHeader("Accept-Ranges")).isEqualTo("bytes");
 		assertThat(this.response.getHeaders("Accept-Ranges").size()).isEqualTo(1);
 	}
diff --git a/spring-webmvc/src/test/java/org/springframework/web/servlet/resource/VersionResourceResolverTests.java b/spring-webmvc/src/test/java/org/springframework/web/servlet/resource/VersionResourceResolverTests.java
index 472b5b77b8..dde2a6f8e3 100644
--- a/spring-webmvc/src/test/java/org/springframework/web/servlet/resource/VersionResourceResolverTests.java
+++ b/spring-webmvc/src/test/java/org/springframework/web/servlet/resource/VersionResourceResolverTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -153,7 +153,7 @@ public class VersionResourceResolverTests {
 		assertThat(actual.getFilename()).isEqualTo(expected.getFilename());
 		verify(this.versionStrategy, times(1)).getResourceVersion(expected);
 		assertThat(actual).isInstanceOf(HttpResource.class);
-		assertThat(((HttpResource)actual).getResponseHeaders().getETag()).isEqualTo("\"" + version + "\"");
+		assertThat(((HttpResource)actual).getResponseHeaders().getETag()).isEqualTo("W/\"" + version + "\"");
 	}
 
 	@Test