springboot-how to solve org.thymeleaf.exceptions.TemplateInputException: Error resolving template template might not exist or might not be accessible by any of the configured Template Resolvers when using spring framework with thymeleaf

Problem

When we run a spring boot or spring mvc application with thymeleaf, sometimes, when we visit the url:

curl http://127.0.0.1:8080/hello2

this error would occur:

This application has no explicit mapping for /error, so you are seeing this as a fallback.

Wed Feb 24 11:10:36 CST 2021
There was an unexpected error (type=Internal Server Error, status=500).
Error resolving template [hello2 bswen], template might not exist or might not be accessible by any of the configured Template Resolvers
org.thymeleaf.exceptions.TemplateInputException: Error resolving template [hello2 bswen], template might not exist or might not be accessible by any of the configured Template Resolvers
    at org.thymeleaf.engine.TemplateManager.resolveTemplate(TemplateManager.java:869)
    at org.thymeleaf.engine.TemplateManager.parseAndProcess(TemplateManager.java:607)
    at org.thymeleaf.TemplateEngine.process(TemplateEngine.java:1098)
    at org.thymeleaf.TemplateEngine.process(TemplateEngine.java:1072)
    at org.thymeleaf.spring5.view.ThymeleafView.renderFragment(ThymeleafView.java:366)
    at org.thymeleaf.spring5.view.ThymeleafView.render(ThymeleafView.java:190)
    at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1393)
    at org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1138)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1077)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:962)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006)
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:626)
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:733)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:327)
    at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:115)
    at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:81)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336)
    at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:119)
    at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:113)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336)
    at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:126)
    at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:81)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336)
    at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:105)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336)
    at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:149)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336)
    at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:63)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336)
    at org.springframework.security.web.authentication.www.BasicAuthenticationFilter.doFilterInternal(BasicAuthenticationFilter.java:178)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336)
    at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:103)
    at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:89)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336)
    at org.springframework.security.web.csrf.CsrfFilter.doFilterInternal(CsrfFilter.java:115)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336)
    at org.springframework.security.web.header.HeaderWriterFilter.doHeadersAfter(HeaderWriterFilter.java:90)
    at org.springframework.security.web.header.HeaderWriterFilter.doFilterInternal(HeaderWriterFilter.java:75)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336)
    at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:110)
    at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:80)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336)
    at org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:55)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336)
    at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:211)
    at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:183)
    at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:358)
    at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:271)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:542)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:143)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:374)
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:888)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1597)
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Thread.java:745)

The core exception is:

There was an unexpected error (type=Internal Server Error, status=500).
Error resolving template [hello2 bswen], template might not exist or might not be accessible by any of the configured Template Resolvers
org.thymeleaf.exceptions.TemplateInputException: Error resolving template [hello2 bswen], template might not exist or might not be accessible by any of the configured Template Resolvers

Spring framework is complaining that it can not find the view resolver for my url.

But why did this happen? I am sure everything is correctly configured, and the codes should be ok.

Environment

  • SpringBoot 1.x and 2.x

The codes and configurations

The project layout is as follows:

.
└── app/
    ├── build.gradle
    └── src/
        └── main/
            ├── java/
            │   └── com.bswen.app9/
            │       ├── MvcConfig
            │       ├── HelloController
            │       └── Main
            └── resources/
                ├── templates/
                │   └── hello.html
                └── application.properties

Let’s check the souce code of build.gradle to view its dependencies:

dependencies {
    ...
    implementation 'org.springframework.boot:spring-boot-starter-web'
    implementation 'org.springframework.boot:spring-boot-starter-thymeleaf'
    ....
}

As the above script shows, we depends on the spring mvc and spring thymeleaf starter, because we are developing a web application.

Let’s check the souce code of HelloController, which defines a method to serve http get request whose url is /hello2, it should return a string:

@Controller
public class HelloController {
    @GetMapping("/hello2")
    public String hello2(Authentication authentication) {
        return String.format("hello2 %s", authentication.getName());
    }
}

There is also a configuration class to configure spring mvc view controllers as follows:

package com.bswen.app9.config;

import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.ViewControllerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

@Configuration
public class MvcConfig implements WebMvcConfigurer {

    public void addViewControllers(ViewControllerRegistry registry) {
        registry.addViewController("/home").setViewName("home");
        registry.addViewController("/").setViewName("home");
        registry.addViewController("/hello").setViewName("hello");
        registry.addViewController("/login").setViewName("login");
    }

}

But when we run this app, we get this exception:

There was an unexpected error (type=Internal Server Error, status=500).

Error resolving template [hello2 bswen], template might not exist or might not be accessible by any of the configured Template Resolvers
org.thymeleaf.exceptions.TemplateInputException: Error resolving template [hello2 bswen], template might not exist or might not be accessible by any of the configured Template Resolvers

Solution

Step 1: Remove the WebMvcConfigurer sub class

Because spring mvc has the default view resolver to thymeleaf, we do not need to configure the views explictly. So we remove the file from our directory. The directory now looks like this:

.
└── app/
    ├── build.gradle
    └── src/
        └── main/
            ├── java/
            │   └── com.bswen.app9/
            │       ├── HelloController
            │       └── Main
            └── resources/
                ├── templates/
                │   └── hello.html
                └── application.properties

Step 2:

Change the Controller to this:

    @GetMapping("/hello2")
    public @ResponseBody String hello2(Authentication authentication) {
        return String.format("hello2 %s", authentication.getName());
    }

We add @ResponseBody to the method, which indicates that this method is returning a plain string, it should not be resolved as a view template.

Rerun the code, the error disappeared.

➜  bswen-springboot23 git:(main) ✗ curl http://127.0.0.1:8080/hello2
hello2 bswen%  

It works!

About the view resolver of spring mvc framework

As the below picture shows, spring relies on the view resolver to resolve the view name from controller.

image-20210224113402290

Thymeleaf is a Java library. It is an XML/XHTML/HTML5 template engine that is able to apply a set of transformations to template files in order to display data and/or text produced by your applications.

If you want to use thymeleaf , just add dependency to the app.

All the example code and config files can be found in this github project.

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