diff --git a/spring-cloud-function-context/src/main/java/org/springframework/cloud/function/context/config/JsonMessageConverter.java b/spring-cloud-function-context/src/main/java/org/springframework/cloud/function/context/config/JsonMessageConverter.java
index 9bad95929..5764f4377 100644
--- a/spring-cloud-function-context/src/main/java/org/springframework/cloud/function/context/config/JsonMessageConverter.java
+++ b/spring-cloud-function-context/src/main/java/org/springframework/cloud/function/context/config/JsonMessageConverter.java
@@ -17,6 +17,7 @@
 package org.springframework.cloud.function.context.config;
 
 import java.lang.reflect.Type;
+import java.nio.charset.StandardCharsets;
 
 import org.springframework.cloud.function.json.JsonMapper;
 import org.springframework.lang.Nullable;
@@ -76,12 +77,16 @@ public class JsonMessageConverter extends AbstractMessageConverter {
 			return message.getPayload();
 		}
 
+
+
 		Type convertToType = conversionHint == null ? targetClass : (Type) conversionHint;
 		try {
 			return this.jsonMapper.fromJson(message.getPayload(), convertToType);
 		}
 		catch (Exception e) {
-			// ignore
+			if (message.getPayload() instanceof byte[] && targetClass.isAssignableFrom(String.class)) {
+				return new String((byte[]) message.getPayload(), StandardCharsets.UTF_8);
+			}
 		}
 		return null;
 	}
diff --git a/spring-cloud-function-rsocket/src/main/java/org/springframework/cloud/function/rsocket/RSocketListenerFunction.java b/spring-cloud-function-rsocket/src/main/java/org/springframework/cloud/function/rsocket/RSocketListenerFunction.java
index 6984fa623..5c6e38d95 100644
--- a/spring-cloud-function-rsocket/src/main/java/org/springframework/cloud/function/rsocket/RSocketListenerFunction.java
+++ b/spring-cloud-function-rsocket/src/main/java/org/springframework/cloud/function/rsocket/RSocketListenerFunction.java
@@ -29,6 +29,7 @@ import org.springframework.cloud.function.context.catalog.SimpleFunctionRegistry
 import org.springframework.messaging.Message;
 import org.springframework.messaging.rsocket.annotation.support.RSocketFrameTypeMessageCondition;
 import org.springframework.messaging.support.MessageBuilder;
+import org.springframework.util.Assert;
 
 
 
@@ -50,6 +51,10 @@ class RSocketListenerFunction implements Function<Message<Flux<byte[]>>, Publish
 
 	@Override
 	public Publisher<?> apply(Message<Flux<byte[]>> input) {
+		Assert.isTrue(this.targetFunction != null, "Failed to discover target function. \n"
+				+ "To fix it you should either provide 'spring.cloud.function.definition' property "
+				+ "or if you are using RSocketRequester provide valid function definition via 'route' "
+				+ "operator (e.g., requester.route(\"echo\"))");
 		FrameType frameType = RSocketFrameTypeMessageCondition.getFrameType(input);
 		switch (frameType) {
 			case REQUEST_FNF: