SpringBoot集成Thymeleaf发送Html邮件报错

由于业务需求需要使用Thymeleaf作为模板发送Html邮件，开发调试过程中发生以下错误

org.thymeleaf.exceptions.TemplateInputException: Error resolving template [assist_notice.html], 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:1059)
    at org.thymeleaf.TemplateEngine.process(TemplateEngine.java:1048)