diff --git a/spring-cloud-function-context/src/main/java/org/springframework/cloud/function/context/catalog/SimpleFunctionRegistry.java b/spring-cloud-function-context/src/main/java/org/springframework/cloud/function/context/catalog/SimpleFunctionRegistry.java
index ffef18541..a4b8be79e 100644
--- a/spring-cloud-function-context/src/main/java/org/springframework/cloud/function/context/catalog/SimpleFunctionRegistry.java
+++ b/spring-cloud-function-context/src/main/java/org/springframework/cloud/function/context/catalog/SimpleFunctionRegistry.java
@@ -1377,10 +1377,22 @@ public class SimpleFunctionRegistry implements FunctionRegistry, FunctionInspect
 					? FunctionTypeUtils.getImmediateGenericType(type, 0)
 					: type;
 			return publisher instanceof Mono
-					? Mono.from(publisher).map(v -> this.convertInputIfNecessary(v, actualType == null ? type : actualType))
-							.doOnError(ex -> logger.error("Failed to convert input", (Throwable) ex))
-					: Flux.from(publisher).map(v -> this.convertInputIfNecessary(v, actualType == null ? type : actualType))
-							.doOnError(ex -> logger.error("Failed to convert input", (Throwable) ex));
+					? Mono.from(publisher).map(v -> {
+						try {
+							return this.convertInputIfNecessary(v, actualType == null ? type : actualType);
+						}
+						catch (Exception e) {
+							throw new IllegalStateException("Failed to convert input", e);
+						}
+					})
+					: Flux.from(publisher).map(v -> {
+						try {
+							return this.convertInputIfNecessary(v, actualType == null ? type : actualType);
+						}
+						catch (Exception e) {
+							throw new IllegalStateException("Failed to convert input", e);
+						}
+					});
 		}
 
 		/*
@@ -1389,10 +1401,22 @@ public class SimpleFunctionRegistry implements FunctionRegistry, FunctionInspect
 		@SuppressWarnings("unchecked")
 		private Object convertOutputPublisherIfNecessary(Publisher publisher, Type type, String[] expectedOutputContentType) {
 			return publisher instanceof Mono
-					? Mono.from(publisher).map(v -> this.convertOutputIfNecessary(v, type, expectedOutputContentType))
-							.doOnError(ex -> logger.error("Failed to convert output", (Throwable) ex))
-					: Flux.from(publisher).map(v -> this.convertOutputIfNecessary(v, type, expectedOutputContentType))
-							.doOnError(ex -> logger.error("Failed to convert output", (Throwable) ex));
+					? Mono.from(publisher).map(v -> {
+						try {
+							return this.convertOutputIfNecessary(v, type, expectedOutputContentType);
+						}
+						catch (Exception e) {
+							throw new IllegalStateException("Failed to convert output", e);
+						}
+					})
+					: Flux.from(publisher).map(v -> {
+						try {
+							return this.convertOutputIfNecessary(v, type, expectedOutputContentType);
+						}
+						catch (Exception e) {
+							throw new IllegalStateException("Failed to convert output", e);
+						}
+					});
 		}
 	}