When the type of the requested parameter is correct and various configurations are correct, a 400 error will appear, and the console will report an error failed to convert value of type ‘Java. Lang. string’ to required type ‘Java. Lang. Integer’; Nested exception is java.lang.numberformatexception: for input string: “XXX”] a similar error may be that the request path set by your control layer and the path of static resources have the same name,
For example:
the page I visit is/user/index.html
and the requestmapping (“user”) of the control layer

when accessing/user/index.html, the user request of the servlet will be followed, and the parameter type may not be correct, which will be 400.
if the correct estimation directly returns the requested JSON result,