diff --git a/spring-webflux/src/main/java/org/springframework/web/reactive/function/server/RouterFunctionBuilder.java b/spring-webflux/src/main/java/org/springframework/web/reactive/function/server/RouterFunctionBuilder.java
index 20e1c0a4be4..aa751f490e1 100644
--- a/spring-webflux/src/main/java/org/springframework/web/reactive/function/server/RouterFunctionBuilder.java
+++ b/spring-webflux/src/main/java/org/springframework/web/reactive/function/server/RouterFunctionBuilder.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.
@@ -24,6 +24,7 @@ import java.util.function.Function;
 import java.util.function.Predicate;
 import java.util.function.Supplier;
 
+import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 
 import org.springframework.core.io.Resource;
@@ -241,9 +242,10 @@ class RouterFunctionBuilder implements RouterFunctions.Builder {
 
 	@Override
 	public RouterFunction<ServerResponse> build() {
-		RouterFunction<ServerResponse> result = this.routerFunctions.stream()
-				.reduce(RouterFunction::and)
-				.orElseThrow(IllegalStateException::new);
+		if (this.routerFunctions.isEmpty()) {
+			throw new IllegalStateException("No routes registered. Register a route with GET(), POST(), etc.");
+		}
+		RouterFunction<ServerResponse> result = new BuiltRouterFunction(this.routerFunctions);
 
 		if (this.filterFunctions.isEmpty()) {
 			return result;
@@ -258,4 +260,30 @@ class RouterFunctionBuilder implements RouterFunctions.Builder {
 		}
 	}
 
+
+	/**
+	 * Router function returned by {@link #build()} that simply iterates over the registered routes.
+	 */
+	private static class BuiltRouterFunction extends RouterFunctions.AbstractRouterFunction<ServerResponse> {
+
+		private List<RouterFunction<ServerResponse>> routerFunctions;
+
+		public BuiltRouterFunction(List<RouterFunction<ServerResponse>> routerFunctions) {
+			Assert.notEmpty(routerFunctions, "RouterFunctions must not be empty");
+			this.routerFunctions = routerFunctions;
+		}
+
+		@Override
+		public Mono<HandlerFunction<ServerResponse>> route(ServerRequest request) {
+			return Flux.fromIterable(this.routerFunctions)
+					.concatMap(routerFunction -> routerFunction.route(request))
+					.next();
+		}
+
+		@Override
+		public void accept(RouterFunctions.Visitor visitor) {
+			this.routerFunctions.forEach(routerFunction -> routerFunction.accept(visitor));
+		}
+	}
+
 }
diff --git a/spring-webflux/src/main/java/org/springframework/web/reactive/function/server/RouterFunctions.java b/spring-webflux/src/main/java/org/springframework/web/reactive/function/server/RouterFunctions.java
index 85e6ee1e202..cd777c38db6 100644
--- a/spring-webflux/src/main/java/org/springframework/web/reactive/function/server/RouterFunctions.java
+++ b/spring-webflux/src/main/java/org/springframework/web/reactive/function/server/RouterFunctions.java
@@ -749,7 +749,7 @@ public abstract class RouterFunctions {
 	}
 
 
-	private abstract static class AbstractRouterFunction<T extends ServerResponse> implements RouterFunction<T> {
+	abstract static class AbstractRouterFunction<T extends ServerResponse> implements RouterFunction<T> {
 
 		@Override
 		public String toString() {
diff --git a/spring-webmvc/src/main/java/org/springframework/web/servlet/function/RouterFunctionBuilder.java b/spring-webmvc/src/main/java/org/springframework/web/servlet/function/RouterFunctionBuilder.java
index 5eb17d9191f..cc23d0144cd 100644
--- a/spring-webmvc/src/main/java/org/springframework/web/servlet/function/RouterFunctionBuilder.java
+++ b/spring-webmvc/src/main/java/org/springframework/web/servlet/function/RouterFunctionBuilder.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.
@@ -237,9 +237,10 @@ class RouterFunctionBuilder implements RouterFunctions.Builder {
 
 	@Override
 	public RouterFunction<ServerResponse> build() {
-		RouterFunction<ServerResponse> result = this.routerFunctions.stream()
-				.reduce(RouterFunction::and)
-				.orElseThrow(IllegalStateException::new);
+		if (this.routerFunctions.isEmpty()) {
+			throw new IllegalStateException("No routes registered. Register a route with GET(), POST(), etc.");
+		}
+		RouterFunction<ServerResponse> result = new BuiltRouterFunction(this.routerFunctions);
 
 		if (this.filterFunctions.isEmpty()) {
 			return result;
@@ -254,4 +255,35 @@ class RouterFunctionBuilder implements RouterFunctions.Builder {
 		}
 	}
 
+
+	/**
+	 * Router function returned by {@link #build()} that simply iterates over the registered routes.
+	 */
+	private static class BuiltRouterFunction extends RouterFunctions.AbstractRouterFunction<ServerResponse> {
+
+		private List<RouterFunction<ServerResponse>> routerFunctions;
+
+		public BuiltRouterFunction(List<RouterFunction<ServerResponse>> routerFunctions) {
+			Assert.notEmpty(routerFunctions, "RouterFunctions must not be empty");
+			this.routerFunctions = routerFunctions;
+		}
+
+		@Override
+		public Optional<HandlerFunction<ServerResponse>> route(ServerRequest request) {
+			for (RouterFunction<ServerResponse> routerFunction : this.routerFunctions) {
+				Optional<HandlerFunction<ServerResponse>> result = routerFunction.route(request);
+				if (result.isPresent()) {
+					return result;
+				}
+			}
+			return Optional.empty();
+		}
+
+		@Override
+		public void accept(RouterFunctions.Visitor visitor) {
+			this.routerFunctions.forEach(routerFunction -> routerFunction.accept(visitor));
+		}
+	}
+
+
 }
diff --git a/spring-webmvc/src/main/java/org/springframework/web/servlet/function/RouterFunctions.java b/spring-webmvc/src/main/java/org/springframework/web/servlet/function/RouterFunctions.java
index 92943358d3d..9122b436293 100644
--- a/spring-webmvc/src/main/java/org/springframework/web/servlet/function/RouterFunctions.java
+++ b/spring-webmvc/src/main/java/org/springframework/web/servlet/function/RouterFunctions.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.
@@ -660,7 +660,7 @@ public abstract class RouterFunctions {
 	}
 
 
-	private abstract static class AbstractRouterFunction<T extends ServerResponse> implements RouterFunction<T> {
+	abstract static class AbstractRouterFunction<T extends ServerResponse> implements RouterFunction<T> {
 
 		@Override
 		public String toString() {