org.springframework.web.multipart.MultipartException: Current request is not a m

<p>单文件上传</p>
<form method="get" action="/excel/uploadExcel" enctype="multipart/form-data">
    <p><input type="file" name="file00"></p>
    <p><span th:if="${msg}"></span></p>
    <input type="submit" value="提交">
</form>

//java单文件导入Excel,保存到target的目录下
   @GetMapping(value = "/uploadExcel")
   public String uploadExcel(@RequestParam("file00") MultipartFile file, Model model) throws IOException {
       try {
           if(file.isEmpty()){
               model.addAttribute("msg","上传失败，请选择文件！");
               return "index";
           }
           ...