升级Spring Boot 2.0.3后Thymeleaf部分页面渲染报错求助

Hey, I’ve dealt with this exact problem when upgrading to Spring Boot 2.0.x, so let’s break down what’s probably happening and how to fix it:

• Check custom Thymeleaf dialects/processors for thread safety
  This exception almost always pops up when a custom dialect or template processor modifies a shared collection (like a global List or Map) without proper synchronization. Thymeleaf parses templates concurrently, so non-thread-safe operations on shared state will trigger this error immediately.
  Fix: Replace your shared collections with thread-safe implementations like CopyOnWriteArrayList or ConcurrentHashMap, or wrap modification logic in a synchronized block.

• Temporarily disable Thymeleaf cache to debug
  Spring Boot 2.0.3’s default Thymeleaf cache setup might have edge cases with concurrent template updates (especially in dev environments). To rule this out, add this line to your application.properties:

  spring.thymeleaf.cache=false
  

  If the error goes away, it’s likely a cache-related concurrency bug. Upgrading Thymeleaf (see next point) should resolve this permanently.

• Upgrade Thymeleaf to a newer patch version
  Spring Boot 2.0.3 ships with Thymeleaf 3.0.9.RELEASE, which has known concurrency issues in template parsing. Manually upgrade to a more stable version (like 3.0.12.RELEASE) to fix these bugs:
  For Maven:

  <dependencies>
      <dependency>
          <groupId>org.thymeleaf</groupId>
          <artifactId>thymeleaf</artifactId>
          <version>3.0.12.RELEASE</version>
      </dependency>
      <dependency>
          <groupId>org.thymeleaf</groupId>
          <artifactId>thymeleaf-spring5</artifactId>
          <version>3.0.12.RELEASE</version>
      </dependency>
  </dependencies>
  

  For Gradle:

  implementation 'org.thymeleaf:thymeleaf:3.0.12.RELEASE'
  implementation 'org.thymeleaf:thymeleaf-spring5:3.0.12.RELEASE'
  

  This version fixes several race conditions in template parsing that cause the exact exception you’re seeing.

• Verify thread safety of beans used in templates
  If your template calls methods on a singleton Spring Bean that isn’t thread-safe (e.g., it has mutable instance variables modified during rendering), concurrent requests will trigger this error. Audit any services, utilities, or components referenced in your mypage.html to ensure they’re thread-safe.

Start with checking your custom Thymeleaf code first—this is the most common culprit. If that doesn’t work, upgrading Thymeleaf should do the trick.

内容的提问来源于stack exchange，提问作者DuSant