diff --git a/spring-cloud-gateway-core/src/main/java/org/springframework/cloud/gateway/config/GatewayAutoConfiguration.java b/spring-cloud-gateway-core/src/main/java/org/springframework/cloud/gateway/config/GatewayAutoConfiguration.java
index 0bc5a710..907420da 100644
--- a/spring-cloud-gateway-core/src/main/java/org/springframework/cloud/gateway/config/GatewayAutoConfiguration.java
+++ b/spring-cloud-gateway-core/src/main/java/org/springframework/cloud/gateway/config/GatewayAutoConfiguration.java
@@ -392,8 +392,8 @@ public class GatewayAutoConfiguration {
 	}
 
 	@Bean
-	public WeightCalculatorWebFilter weightCalculatorWebFilter(Validator validator) {
-		return new WeightCalculatorWebFilter(validator);
+	public WeightCalculatorWebFilter weightCalculatorWebFilter(Validator validator, ObjectProvider<RouteLocator> routeLocator) {
+		return new WeightCalculatorWebFilter(validator, routeLocator);
 	}
 
 	/*@Bean
diff --git a/spring-cloud-gateway-core/src/main/java/org/springframework/cloud/gateway/filter/WeightCalculatorWebFilter.java b/spring-cloud-gateway-core/src/main/java/org/springframework/cloud/gateway/filter/WeightCalculatorWebFilter.java
index 0868e438..72f8d567 100644
--- a/spring-cloud-gateway-core/src/main/java/org/springframework/cloud/gateway/filter/WeightCalculatorWebFilter.java
+++ b/spring-cloud-gateway-core/src/main/java/org/springframework/cloud/gateway/filter/WeightCalculatorWebFilter.java
@@ -27,9 +27,13 @@ import java.util.concurrent.atomic.AtomicInteger;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
-import org.jetbrains.annotations.NotNull;
+import reactor.core.publisher.Mono;
+
+import org.springframework.beans.factory.ObjectProvider;
 import org.springframework.cloud.gateway.event.PredicateArgsEvent;
+import org.springframework.cloud.gateway.event.RefreshRoutesEvent;
 import org.springframework.cloud.gateway.event.WeightDefinedEvent;
+import org.springframework.cloud.gateway.route.RouteLocator;
 import org.springframework.cloud.gateway.support.ConfigurationUtils;
 import org.springframework.cloud.gateway.support.WeightConfig;
 import org.springframework.context.ApplicationEvent;
@@ -43,8 +47,6 @@ import org.springframework.web.server.WebFilterChain;
 
 import static org.springframework.cloud.gateway.support.ServerWebExchangeUtils.WEIGHT_ATTR;
 
-import reactor.core.publisher.Mono;
-
 /**
  * @author Spencer Gibb
  */
@@ -55,17 +57,24 @@ public class WeightCalculatorWebFilter implements WebFilter, Ordered, SmartAppli
 	public static final int WEIGHT_CALC_FILTER_ORDER = 10001;
 
 	private final Validator validator;
+	private final ObjectProvider<RouteLocator> routeLocator;
 	private Random random = new Random();
 	private int order = WEIGHT_CALC_FILTER_ORDER;
 
 	private Map<String, GroupWeightConfig> groupWeights = new ConcurrentHashMap<>();
 
 	/* for testing */ WeightCalculatorWebFilter() {
-		this(null);
+		this(null, null);
 	}
 
+	@Deprecated
 	public WeightCalculatorWebFilter(Validator validator) {
+		this(validator, null);
+	}
+
+	public WeightCalculatorWebFilter(Validator validator, ObjectProvider<RouteLocator> routeLocator) {
 		this.validator = validator;
+		this.routeLocator = routeLocator;
 	}
 
 	@Override
@@ -84,7 +93,8 @@ public class WeightCalculatorWebFilter implements WebFilter, Ordered, SmartAppli
 	@Override
 	public boolean supportsEventType(Class<? extends ApplicationEvent> eventType) {
 		return PredicateArgsEvent.class.isAssignableFrom(eventType) || // config file
-				WeightDefinedEvent.class.isAssignableFrom(eventType);  // java dsl
+				WeightDefinedEvent.class.isAssignableFrom(eventType) ||  // java dsl
+				RefreshRoutesEvent.class.isAssignableFrom(eventType); // force initialization
 	}
 
 	@Override
@@ -98,6 +108,8 @@ public class WeightCalculatorWebFilter implements WebFilter, Ordered, SmartAppli
 			handle((PredicateArgsEvent) event);
 		} else if (event instanceof WeightDefinedEvent) {
 			addWeightConfig(((WeightDefinedEvent)event).getWeightConfig());
+		} else if (event instanceof RefreshRoutesEvent && routeLocator != null) {
+			routeLocator.ifAvailable(locator -> locator.getRoutes().subscribe()); // forces initialization
 		}
 
 	}
@@ -197,7 +209,6 @@ public class WeightCalculatorWebFilter implements WebFilter, Ordered, SmartAppli
 		return chain.filter(exchange);
 	}
 
-	@NotNull
 	/* for testing */ static Map<String, String> getWeights(ServerWebExchange exchange) {
 		Map<String, String> weights = exchange.getAttribute(WEIGHT_ATTR);
 
diff --git a/spring-cloud-gateway-core/src/main/java/org/springframework/cloud/gateway/handler/predicate/WeightRoutePredicateFactory.java b/spring-cloud-gateway-core/src/main/java/org/springframework/cloud/gateway/handler/predicate/WeightRoutePredicateFactory.java
index 5d41d33c..4ccd3a48 100644
--- a/spring-cloud-gateway-core/src/main/java/org/springframework/cloud/gateway/handler/predicate/WeightRoutePredicateFactory.java
+++ b/spring-cloud-gateway-core/src/main/java/org/springframework/cloud/gateway/handler/predicate/WeightRoutePredicateFactory.java
@@ -92,6 +92,8 @@ public class WeightRoutePredicateFactory extends AbstractRoutePredicateFactory<W
 				}
 
 				return routeId.equals(chosenRoute);
+			} else if (log.isTraceEnabled()) {
+				log.trace("no weights found for group: "+ group + ", current route: " + routeId);
 			}
 
 			return false;
diff --git a/spring-cloud-gateway-core/src/test/java/org/springframework/cloud/gateway/handler/predicate/WeightRoutePredicateFactoryYaml404Tests.java b/spring-cloud-gateway-core/src/test/java/org/springframework/cloud/gateway/handler/predicate/WeightRoutePredicateFactoryYaml404Tests.java
new file mode 100644
index 00000000..fa00bf44
--- /dev/null
+++ b/spring-cloud-gateway-core/src/test/java/org/springframework/cloud/gateway/handler/predicate/WeightRoutePredicateFactoryYaml404Tests.java
@@ -0,0 +1,81 @@
+/*
+ * Copyright 2013-2019 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.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package org.springframework.cloud.gateway.handler.predicate;
+
+import java.util.Random;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.SpringBootConfiguration;
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.cloud.gateway.filter.WeightCalculatorWebFilter;
+import org.springframework.cloud.gateway.test.BaseWebClientTests;
+import org.springframework.context.annotation.Import;
+import org.springframework.http.HttpHeaders;
+import org.springframework.test.annotation.DirtiesContext;
+import org.springframework.test.context.ActiveProfiles;
+import org.springframework.test.context.junit4.SpringRunner;
+
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+import static org.springframework.boot.test.context.SpringBootTest.WebEnvironment.RANDOM_PORT;
+
+@RunWith(SpringRunner.class)
+@SpringBootTest(webEnvironment = RANDOM_PORT)
+@ActiveProfiles("weights-404")
+@DirtiesContext
+public class WeightRoutePredicateFactoryYaml404Tests extends BaseWebClientTests {
+
+	@Autowired
+	private WeightCalculatorWebFilter filter;
+
+	@Test
+	public void weightsFromYamlNot404() {
+		filter.setRandom(getRandom(0.5));
+
+		testClient.get().uri("/get")
+				.header(HttpHeaders.HOST, "www.weight4041.org")
+				.exchange()
+				.expectStatus().isOk()
+				.expectHeader().valueEquals(ROUTE_ID_HEADER, "weight_first_404_test_1");
+	}
+
+	@EnableAutoConfiguration
+	@SpringBootConfiguration
+	@Import(DefaultTestConfig.class)
+	public static class TestConfig {
+
+		public TestConfig(WeightCalculatorWebFilter filter) {
+			Random random = getRandom(0.4);
+
+			filter.setRandom(random);
+		}
+
+	}
+
+	private static Random getRandom(double value) {
+		Random random = mock(Random.class);
+		when(random.nextDouble())
+                .thenReturn(value);
+		return random;
+	}
+
+}
diff --git a/spring-cloud-gateway-core/src/test/resources/application-weights-404.yml b/spring-cloud-gateway-core/src/test/resources/application-weights-404.yml
new file mode 100644
index 00000000..cc264b95
--- /dev/null
+++ b/spring-cloud-gateway-core/src/test/resources/application-weights-404.yml
@@ -0,0 +1,22 @@
+test:
+  uri: lb://testservice
+
+spring:
+  cloud:
+    gateway:
+      default-filters:
+        - PrefixPath=/httpbin
+      routes:
+        # =====================================
+      - id: weight_first_404_test_1
+        uri: ${test.uri}
+        predicates:
+          - Host=**.weight4041.org
+          - Weight=group404, 8
+
+        # =====================================
+      - id: weight_first_404_test_2
+        uri: ${test.uri}
+        predicates:
+          - Host=**.weight4042.org
+          - Weight=group404, 2