diff --git a/spring-boot-project/spring-boot-test-autoconfigure/build.gradle b/spring-boot-project/spring-boot-test-autoconfigure/build.gradle
index 6bdaa001afbd..b9540733436a 100644
--- a/spring-boot-project/spring-boot-test-autoconfigure/build.gradle
+++ b/spring-boot-project/spring-boot-test-autoconfigure/build.gradle
@@ -84,6 +84,7 @@ dependencies {
 	testImplementation("org.testcontainers:mongodb")
 	testImplementation("org.testcontainers:neo4j")
 	testImplementation("org.testcontainers:testcontainers")
+	testImplementation("org.thymeleaf:thymeleaf")
 
 	testRuntimeOnly("org.junit.platform:junit-platform-launcher")
 }
diff --git a/spring-boot-project/spring-boot-test-autoconfigure/src/main/java/org/springframework/boot/test/autoconfigure/web/reactive/WebFluxTypeExcludeFilter.java b/spring-boot-project/spring-boot-test-autoconfigure/src/main/java/org/springframework/boot/test/autoconfigure/web/reactive/WebFluxTypeExcludeFilter.java
index a7d3dd0b9a7c..2a34559041a1 100644
--- a/spring-boot-project/spring-boot-test-autoconfigure/src/main/java/org/springframework/boot/test/autoconfigure/web/reactive/WebFluxTypeExcludeFilter.java
+++ b/spring-boot-project/spring-boot-test-autoconfigure/src/main/java/org/springframework/boot/test/autoconfigure/web/reactive/WebFluxTypeExcludeFilter.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2020 the original author or authors.
+ * Copyright 2012-2021 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.
@@ -21,14 +21,13 @@
 import java.util.LinkedHashSet;
 import java.util.Set;
 
-import com.fasterxml.jackson.databind.Module;
-
 import org.springframework.boot.context.TypeExcludeFilter;
 import org.springframework.boot.jackson.JsonComponent;
 import org.springframework.boot.test.autoconfigure.filter.StandardAnnotationCustomizableTypeExcludeFilter;
 import org.springframework.core.convert.converter.Converter;
 import org.springframework.core.convert.converter.GenericConverter;
 import org.springframework.stereotype.Controller;
+import org.springframework.util.ClassUtils;
 import org.springframework.util.ObjectUtils;
 import org.springframework.web.bind.annotation.ControllerAdvice;
 import org.springframework.web.reactive.config.WebFluxConfigurer;
@@ -45,6 +44,9 @@ public final class WebFluxTypeExcludeFilter extends StandardAnnotationCustomizab
 
 	private static final Class<?>[] NO_CONTROLLERS = {};
 
+	private static final String[] OPTIONAL_INCLUDES = { "com.fasterxml.jackson.databind.Module",
+			"org.thymeleaf.dialect.IDialect" };
+
 	private static final Set<Class<?>> DEFAULT_INCLUDES;
 
 	static {
@@ -56,10 +58,13 @@ public final class WebFluxTypeExcludeFilter extends StandardAnnotationCustomizab
 		includes.add(GenericConverter.class);
 		includes.add(WebExceptionHandler.class);
 		includes.add(WebFilter.class);
-		try {
-			includes.add(Module.class);
-		}
-		catch (Throwable ex) {
+		for (String optionalInclude : OPTIONAL_INCLUDES) {
+			try {
+				includes.add(ClassUtils.forName(optionalInclude, null));
+			}
+			catch (Exception ex) {
+				// Ignore
+			}
 		}
 		DEFAULT_INCLUDES = Collections.unmodifiableSet(includes);
 	}
diff --git a/spring-boot-project/spring-boot-test-autoconfigure/src/main/java/org/springframework/boot/test/autoconfigure/web/servlet/WebMvcTypeExcludeFilter.java b/spring-boot-project/spring-boot-test-autoconfigure/src/main/java/org/springframework/boot/test/autoconfigure/web/servlet/WebMvcTypeExcludeFilter.java
index 193874534800..f2be9723b73e 100644
--- a/spring-boot-project/spring-boot-test-autoconfigure/src/main/java/org/springframework/boot/test/autoconfigure/web/servlet/WebMvcTypeExcludeFilter.java
+++ b/spring-boot-project/spring-boot-test-autoconfigure/src/main/java/org/springframework/boot/test/autoconfigure/web/servlet/WebMvcTypeExcludeFilter.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2020 the original author or authors.
+ * Copyright 2012-2021 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.
@@ -21,8 +21,6 @@
 import java.util.LinkedHashSet;
 import java.util.Set;
 
-import com.fasterxml.jackson.databind.Module;
-
 import org.springframework.boot.context.TypeExcludeFilter;
 import org.springframework.boot.jackson.JsonComponent;
 import org.springframework.boot.test.autoconfigure.filter.StandardAnnotationCustomizableTypeExcludeFilter;
@@ -51,9 +49,9 @@ public final class WebMvcTypeExcludeFilter extends StandardAnnotationCustomizabl
 
 	private static final Class<?>[] NO_CONTROLLERS = {};
 
-	private static final String[] OPTIONAL_INCLUDES = {
+	private static final String[] OPTIONAL_INCLUDES = { "com.fasterxml.jackson.databind.Module",
 			"org.springframework.security.config.annotation.web.WebSecurityConfigurer",
-			"org.springframework.security.web.SecurityFilterChain" };
+			"org.springframework.security.web.SecurityFilterChain", "org.thymeleaf.dialect.IDialect" };
 
 	private static final Set<Class<?>> DEFAULT_INCLUDES;
 
@@ -71,11 +69,6 @@ public final class WebMvcTypeExcludeFilter extends StandardAnnotationCustomizabl
 		includes.add(Converter.class);
 		includes.add(GenericConverter.class);
 		includes.add(HandlerInterceptor.class);
-		try {
-			includes.add(Module.class);
-		}
-		catch (Throwable ex) {
-		}
 		for (String optionalInclude : OPTIONAL_INCLUDES) {
 			try {
 				includes.add(ClassUtils.forName(optionalInclude, null));
diff --git a/spring-boot-project/spring-boot-test-autoconfigure/src/test/java/org/springframework/boot/test/autoconfigure/web/reactive/WebFluxTypeExcludeFilterTests.java b/spring-boot-project/spring-boot-test-autoconfigure/src/test/java/org/springframework/boot/test/autoconfigure/web/reactive/WebFluxTypeExcludeFilterTests.java
index a8ce35b10194..6eff59b9fb2d 100644
--- a/spring-boot-project/spring-boot-test-autoconfigure/src/test/java/org/springframework/boot/test/autoconfigure/web/reactive/WebFluxTypeExcludeFilterTests.java
+++ b/spring-boot-project/spring-boot-test-autoconfigure/src/test/java/org/springframework/boot/test/autoconfigure/web/reactive/WebFluxTypeExcludeFilterTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2020 the original author or authors.
+ * Copyright 2012-2021 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.
@@ -20,6 +20,7 @@
 
 import com.fasterxml.jackson.databind.module.SimpleModule;
 import org.junit.jupiter.api.Test;
+import org.thymeleaf.dialect.IDialect;
 import reactor.core.publisher.Mono;
 
 import org.springframework.context.annotation.ComponentScan.Filter;
@@ -59,6 +60,7 @@ void matchWhenHasNoControllers() throws Exception {
 		assertThat(excludes(filter, ExampleRepository.class)).isTrue();
 		assertThat(excludes(filter, ExampleWebFilter.class)).isFalse();
 		assertThat(excludes(filter, ExampleModule.class)).isFalse();
+		assertThat(excludes(filter, ExampleDialect.class)).isFalse();
 	}
 
 	@Test
@@ -72,6 +74,7 @@ void matchWhenHasController() throws Exception {
 		assertThat(excludes(filter, ExampleRepository.class)).isTrue();
 		assertThat(excludes(filter, ExampleWebFilter.class)).isFalse();
 		assertThat(excludes(filter, ExampleModule.class)).isFalse();
+		assertThat(excludes(filter, ExampleDialect.class)).isFalse();
 	}
 
 	@Test
@@ -85,6 +88,7 @@ void matchNotUsingDefaultFilters() throws Exception {
 		assertThat(excludes(filter, ExampleRepository.class)).isTrue();
 		assertThat(excludes(filter, ExampleWebFilter.class)).isTrue();
 		assertThat(excludes(filter, ExampleModule.class)).isTrue();
+		assertThat(excludes(filter, ExampleDialect.class)).isTrue();
 	}
 
 	@Test
@@ -98,6 +102,7 @@ void matchWithIncludeFilter() throws Exception {
 		assertThat(excludes(filter, ExampleRepository.class)).isFalse();
 		assertThat(excludes(filter, ExampleWebFilter.class)).isFalse();
 		assertThat(excludes(filter, ExampleModule.class)).isFalse();
+		assertThat(excludes(filter, ExampleDialect.class)).isFalse();
 	}
 
 	@Test
@@ -111,6 +116,7 @@ void matchWithExcludeFilter() throws Exception {
 		assertThat(excludes(filter, ExampleRepository.class)).isTrue();
 		assertThat(excludes(filter, ExampleWebFilter.class)).isFalse();
 		assertThat(excludes(filter, ExampleModule.class)).isFalse();
+		assertThat(excludes(filter, ExampleDialect.class)).isFalse();
 	}
 
 	private boolean excludes(WebFluxTypeExcludeFilter filter, Class<?> type) throws IOException {
@@ -185,4 +191,13 @@ static class ExampleModule extends SimpleModule {
 
 	}
 
+	static class ExampleDialect implements IDialect {
+
+		@Override
+		public String getName() {
+			return "example";
+		}
+
+	}
+
 }
diff --git a/spring-boot-project/spring-boot-test-autoconfigure/src/test/java/org/springframework/boot/test/autoconfigure/web/servlet/WebMvcTypeExcludeFilterTests.java b/spring-boot-project/spring-boot-test-autoconfigure/src/test/java/org/springframework/boot/test/autoconfigure/web/servlet/WebMvcTypeExcludeFilterTests.java
index 9ca2e188c562..ce8477be4223 100644
--- a/spring-boot-project/spring-boot-test-autoconfigure/src/test/java/org/springframework/boot/test/autoconfigure/web/servlet/WebMvcTypeExcludeFilterTests.java
+++ b/spring-boot-project/spring-boot-test-autoconfigure/src/test/java/org/springframework/boot/test/autoconfigure/web/servlet/WebMvcTypeExcludeFilterTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2020 the original author or authors.
+ * Copyright 2012-2021 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.
@@ -20,6 +20,7 @@
 
 import com.fasterxml.jackson.databind.module.SimpleModule;
 import org.junit.jupiter.api.Test;
+import org.thymeleaf.dialect.IDialect;
 
 import org.springframework.context.annotation.ComponentScan.Filter;
 import org.springframework.context.annotation.FilterType;
@@ -61,6 +62,7 @@ void matchWhenHasNoControllers() throws Exception {
 		assertThat(excludes(filter, SecurityFilterChain.class)).isFalse();
 		assertThat(excludes(filter, ExampleHandlerInterceptor.class)).isFalse();
 		assertThat(excludes(filter, ExampleModule.class)).isFalse();
+		assertThat(excludes(filter, ExampleDialect.class)).isFalse();
 	}
 
 	@Test
@@ -77,6 +79,7 @@ void matchWhenHasController() throws Exception {
 		assertThat(excludes(filter, SecurityFilterChain.class)).isFalse();
 		assertThat(excludes(filter, ExampleHandlerInterceptor.class)).isFalse();
 		assertThat(excludes(filter, ExampleModule.class)).isFalse();
+		assertThat(excludes(filter, ExampleDialect.class)).isFalse();
 	}
 
 	@Test
@@ -93,6 +96,7 @@ void matchNotUsingDefaultFilters() throws Exception {
 		assertThat(excludes(filter, SecurityFilterChain.class)).isTrue();
 		assertThat(excludes(filter, ExampleHandlerInterceptor.class)).isTrue();
 		assertThat(excludes(filter, ExampleModule.class)).isTrue();
+		assertThat(excludes(filter, ExampleDialect.class)).isTrue();
 	}
 
 	@Test
@@ -107,6 +111,7 @@ void matchWithIncludeFilter() throws Exception {
 		assertThat(excludes(filter, ExampleRepository.class)).isFalse();
 		assertThat(excludes(filter, ExampleHandlerInterceptor.class)).isFalse();
 		assertThat(excludes(filter, ExampleModule.class)).isFalse();
+		assertThat(excludes(filter, ExampleDialect.class)).isFalse();
 	}
 
 	@Test
@@ -123,6 +128,7 @@ void matchWithExcludeFilter() throws Exception {
 		assertThat(excludes(filter, SecurityFilterChain.class)).isFalse();
 		assertThat(excludes(filter, ExampleHandlerInterceptor.class)).isFalse();
 		assertThat(excludes(filter, ExampleModule.class)).isFalse();
+		assertThat(excludes(filter, ExampleDialect.class)).isFalse();
 	}
 
 	private boolean excludes(WebMvcTypeExcludeFilter filter, Class<?> type) throws IOException {
@@ -200,4 +206,13 @@ static class ExampleModule extends SimpleModule {
 
 	}
 
+	static class ExampleDialect implements IDialect {
+
+		@Override
+		public String getName() {
+			return "example";
+		}
+
+	}
+
 }