diff --git a/spring-cloud-gateway-core/src/main/java/org/springframework/cloud/gateway/actuate/GatewayEndpoint.java b/spring-cloud-gateway-core/src/main/java/org/springframework/cloud/gateway/actuate/GatewayEndpoint.java
index 4363ed76..eca32166 100644
--- a/spring-cloud-gateway-core/src/main/java/org/springframework/cloud/gateway/actuate/GatewayEndpoint.java
+++ b/spring-cloud-gateway-core/src/main/java/org/springframework/cloud/gateway/actuate/GatewayEndpoint.java
@@ -128,21 +128,22 @@ public class GatewayEndpoint implements ApplicationEventPublisherAware {/*extend
 http POST :8080/admin/gateway/routes/apiaddreqhead uri=http://httpbin.org:80 predicates:='["Host=**.apiaddrequestheader.org", "Path=/headers"]' filters:='["AddRequestHeader=X-Request-ApiFoo, ApiBar"]'
 */
 	@PostMapping("/routes/{id}")
+	@SuppressWarnings("unchecked")
 	public Mono<ResponseEntity<Void>> save(@PathVariable String id, @RequestBody Mono<RouteDefinition> route) {
 		return this.routeDefinitionWriter.save(route.map(r ->  {
 			r.setId(id);
 			log.debug("Saving route: " + route);
 			return r;
-		})).then(() ->
+		})).then(Mono.defer(() ->
 			Mono.just(ResponseEntity.created(URI.create("/routes/"+id)).build())
-		);
+		));
 	}
 
 	@DeleteMapping("/routes/{id}")
 	public Mono<ResponseEntity<Object>> delete(@PathVariable String id) {
 		return this.routeDefinitionWriter.delete(Mono.just(id))
-				.then(() -> Mono.just(ResponseEntity.ok().build()))
-				.otherwise(t -> t instanceof NotFoundException, t -> Mono.just(ResponseEntity.notFound().build()));
+				.then(Mono.defer(() -> Mono.just(ResponseEntity.ok().build())))
+				.onErrorResume(t -> t instanceof NotFoundException, t -> Mono.just(ResponseEntity.notFound().build()));
 	}
 
 	@GetMapping("/routes/{id}")
@@ -151,7 +152,7 @@ http POST :8080/admin/gateway/routes/apiaddreqhead uri=http://httpbin.org:80 pre
 				.filter(route -> route.getId().equals(id))
 				.singleOrEmpty()
 				.map(route -> ResponseEntity.ok(route))
-				.otherwiseIfEmpty(Mono.just(ResponseEntity.notFound().build()));
+				.switchIfEmpty(Mono.just(ResponseEntity.notFound().build()));
 	}
 
 	@GetMapping("/routes/{id}/combinedfilters")
diff --git a/spring-cloud-gateway-core/src/main/java/org/springframework/cloud/gateway/filter/WriteResponseFilter.java b/spring-cloud-gateway-core/src/main/java/org/springframework/cloud/gateway/filter/WriteResponseFilter.java
index 0f88ada1..985671d6 100644
--- a/spring-cloud-gateway-core/src/main/java/org/springframework/cloud/gateway/filter/WriteResponseFilter.java
+++ b/spring-cloud-gateway-core/src/main/java/org/springframework/cloud/gateway/filter/WriteResponseFilter.java
@@ -51,7 +51,7 @@ public class WriteResponseFilter implements GlobalFilter, Ordered {
 	public Mono<Void> filter(ServerWebExchange exchange, WebFilterChain chain) {
 		// NOTICE: nothing in "pre" filter stage as CLIENT_RESPONSE_ATTR is not added
 		// until the WebHandler is run
-		return chain.filter(exchange).then(() -> {
+		return chain.filter(exchange).then(Mono.defer(() -> {
 			HttpClientResponse clientResponse = getAttribute(exchange, CLIENT_RESPONSE_ATTR, HttpClientResponse.class);
 			if (clientResponse == null) {
 				return Mono.empty();
@@ -67,7 +67,7 @@ public class WriteResponseFilter implements GlobalFilter, Ordered {
 					.map(factory::wrap);
 
 			return response.writeWith(body);
-		});
+		}));
 	}
 
 }
diff --git a/spring-cloud-gateway-core/src/main/java/org/springframework/cloud/gateway/filter/factory/RedirectToWebFilterFactory.java b/spring-cloud-gateway-core/src/main/java/org/springframework/cloud/gateway/filter/factory/RedirectToWebFilterFactory.java
index a88bc824..b394f235 100644
--- a/spring-cloud-gateway-core/src/main/java/org/springframework/cloud/gateway/filter/factory/RedirectToWebFilterFactory.java
+++ b/spring-cloud-gateway-core/src/main/java/org/springframework/cloud/gateway/filter/factory/RedirectToWebFilterFactory.java
@@ -61,7 +61,7 @@ public class RedirectToWebFilterFactory implements WebFilterFactory {
 		}
 
 		return (exchange, chain) ->
-			chain.filter(exchange).then(() -> {
+			chain.filter(exchange).then(Mono.defer(() -> {
 				if (!exchange.getResponse().isCommitted()) {
 					setResponseStatus(exchange, httpStatus);
 
@@ -70,7 +70,7 @@ public class RedirectToWebFilterFactory implements WebFilterFactory {
 					return response.setComplete();
 				}
 				return Mono.empty();
-			});
+			}));
 	}
 
 }
diff --git a/spring-cloud-gateway-core/src/main/java/org/springframework/cloud/gateway/filter/factory/SetStatusWebFilterFactory.java b/spring-cloud-gateway-core/src/main/java/org/springframework/cloud/gateway/filter/factory/SetStatusWebFilterFactory.java
index c4efefce..570a3ed5 100644
--- a/spring-cloud-gateway-core/src/main/java/org/springframework/cloud/gateway/filter/factory/SetStatusWebFilterFactory.java
+++ b/spring-cloud-gateway-core/src/main/java/org/springframework/cloud/gateway/filter/factory/SetStatusWebFilterFactory.java
@@ -56,13 +56,13 @@ public class SetStatusWebFilterFactory implements WebFilterFactory {
 			return chain.filter(exchange);*/
 
 			// option 2 (runs in reverse filter order)
-			return chain.filter(exchange).then(() -> {
+			return chain.filter(exchange).then(Mono.defer(() -> {
 				// check not really needed, since it is guarded in setStatusCode, but it's a good example
 				if (!exchange.getResponse().isCommitted()) {
 					setResponseStatus(exchange, httpStatus);
 				}
 				return Mono.empty();
-			});
+			}));
 		};
 	}
 
diff --git a/spring-cloud-gateway-core/src/main/java/org/springframework/cloud/gateway/handler/RoutePredicateHandlerMapping.java b/spring-cloud-gateway-core/src/main/java/org/springframework/cloud/gateway/handler/RoutePredicateHandlerMapping.java
index 8e2c4de1..8d70cfe5 100644
--- a/spring-cloud-gateway-core/src/main/java/org/springframework/cloud/gateway/handler/RoutePredicateHandlerMapping.java
+++ b/spring-cloud-gateway-core/src/main/java/org/springframework/cloud/gateway/handler/RoutePredicateHandlerMapping.java
@@ -58,12 +58,12 @@ public class RoutePredicateHandlerMapping extends AbstractHandlerMapping {
 
 					exchange.getAttributes().put(GATEWAY_ROUTE_ATTR, r);
 					return Mono.just(webHandler);
-				}).otherwiseIfEmpty(Mono.empty().then(() -> {
+				}).switchIfEmpty(Mono.empty().then(Mono.defer(() -> {
 					if (logger.isTraceEnabled()) {
 						logger.trace("No RouteDefinition found for [" + getExchangeDesc(exchange) + "]");
 					}
 					return Mono.empty();
-				}));
+				})));
 	}
 
 	//TODO: get desc from factory?
diff --git a/spring-cloud-gateway-core/src/test/java/org/springframework/cloud/gateway/test/GatewayIntegrationTests.java b/spring-cloud-gateway-core/src/test/java/org/springframework/cloud/gateway/test/GatewayIntegrationTests.java
index aabb9cfe..a5e10fc0 100644
--- a/spring-cloud-gateway-core/src/test/java/org/springframework/cloud/gateway/test/GatewayIntegrationTests.java
+++ b/spring-cloud-gateway-core/src/test/java/org/springframework/cloud/gateway/test/GatewayIntegrationTests.java
@@ -64,7 +64,7 @@ public class GatewayIntegrationTests extends BaseWebClientTests {
 		Mono<Map> result = webClient.post()
 				.uri("/headers")
 				.contentType(MediaType.APPLICATION_JSON_UTF8)
-				.body("testdata")
+				.syncBody("testdata")
 				.header("Host", "www.complexcontenttype.org")
 				.exchange()
 				.flatMap(response -> response.body(toMono(Map.class)));
diff --git a/spring-cloud-gateway-core/src/test/java/org/springframework/cloud/gateway/test/PostTests.java b/spring-cloud-gateway-core/src/test/java/org/springframework/cloud/gateway/test/PostTests.java
index 1f180ddd..15b4d35a 100644
--- a/spring-cloud-gateway-core/src/test/java/org/springframework/cloud/gateway/test/PostTests.java
+++ b/spring-cloud-gateway-core/src/test/java/org/springframework/cloud/gateway/test/PostTests.java
@@ -47,7 +47,7 @@ public class PostTests extends BaseWebClientTests {
 		Mono<Map> result = webClient.post()
 				.uri("/post")
 				.header("Host", "www.example.org")
-				.body("testdata")
+				.syncBody("testdata")
 				.exchange()
 				.flatMap(response -> response.body(toMono(Map.class)));