Error resolving template [index], template might not exist or might not be accessible by any of the configured Template Resolvers

you might be facing the below exception in spring boot thymeleaf:

Exception processing template "index": Error resolving template [index], template might not exist or might not be accessible by any of the configured Template Resolvers

org.thymeleaf.exceptions.TemplateInputException: Error resolving template [index], 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) ~[thymeleaf-3.0.15.RELEASE.jar:3.0.15.RELEASE]
	at org.thymeleaf.engine.TemplateManager.parseAndProcess(TemplateManager.java:607) ~[thymeleaf-3.0.15.RELEASE.jar:3.0.15.RELEASE]

Solution

Add below in application.yaml file:

spring:
  thymeleaf:
    prefix: classpath:/templates/
    suffix: .html

application.properties:

spring.thymeleaf.prefix=classpath:/templates/
spring.thymeleaf.suffix=.html

another possibility is that make sure that template html files are copied in correct folder:

src/main/resources/templates 

Please check this tutorial for working thymeleaf example:

Thanks for reading.