使用el-upload进行服务端直传时出现错误

<el-upload
      class="avatar-uploader"
       action="#
      :data="policyObj"
      :show-file-list="false"
      :on-success="handleUploadSuccess"
       :before-upload="beforeUpload">
  <img v-if="dataForm.coverUrl" :src="dataForm.coverUrl" class="avatar">
  <i v-else class="el-icon-plus avatar-uploader-icon"></i>
</el-upload>

beforeUpload(file) {
        console.log("beforeUpload")
        this.$http({
              url: this.$http.adornUrl(`/third/oss/policy`),
              method: 'post',
              params: this.$http.adornParams()
            }).then(({data}) => {
              console.log(data)
              if (data && data.code === 0) {
                this.policyObj.policy = data.data.policy
                this.policyObj.signature = data.data.signature
                this.policyObj.ossaccessKeyId = data.data.accessId
                this.policyObj.dir = data.data.dir
                this.policyObj.host = data.data.host
                this.policyObj.key = data.data.host+'/'+data.data.dir+this.getUUID()+file.name
                console.log(this.policyObj)
              }
            })
    },

     beforeUpload(file) {
        console.log("beforeUpload")
        return new Promise((resolve,reject)=>{
          this.$http({
            url: this.$http.adornUrl(`/third/oss/policy`),
            method: "get",
            params: this.$http.adornParams({})
          }).then(({data})=>{
            this.policyObj.policy = data.data.policy
            this.policyObj.signature = data.data.signature
            this.policyObj.ossaccessKeyId = data.data.accessId
            this.policyObj.dir = data.data.dir
            this.policyObj.host = data.data.host
            this.policyObj.key = data.data.host+'/'+data.data.dir+this.getUUID()+file.name
            resolve(true)
          }).catch(err=>{
            reject(false)
          })
        })
    }