This problem occurs when spring boot} integrates thymeleaf

By querying other people’s blogs. I understand that there are several possible errors

1 when the method corresponding to your controller layer returns the HTML path and name, add an additional /.

For example, return “/index”. If this ‘/’ causes an error, the solution is to remove the ‘/’ in front of the return, such as return “/index”

2. Introduction package problem (I solved it this way)

Add dependency in porn

<dependency> 
<groupId>net.sourceforge.nekohtml</groupId> 
<artifactId>nekohtml</artifactId> 
<version>1.9.22</version> 
</dependency>