Cannot update data using vue.js in laravel

In my update form i have a file field that i want to update so i'm using following code and created a form object but when i pass form object i cannot get the data of form object in my controller.

let formData = new FormData();
        formData.append('name', this.form.name);
        formData.append('description', this.form.description);   
        formData.append('file_update', this.form.file_update);    

        axios.put(`/api/saveClass/${this.ItemId}`,formData,{headers:header})
        .then((response)=>{

            var msg = response.data.message;
            if(response.status ==200){
                this.$Progress.finish();
                  
            }else{
                this.$Progress.fail();
            }
              
            this.$router.push(`/api/showClass`);
        })
        .catch(() => {
            
        });
        },

Laravel Controller:

  public function update(Request $request,$id)
    {
       
        $ItemStore = class::find($id);
        $this->validate($request,[
            'name' => 'required|string|max:191|unique:class,name,'.$id,
            'description' => 'required',
        ]);

     }

I am getting name and description field is required but i'm passing data to it.

via Chebli Mohamed