this.$refs.formValidate.resetFields() Cannot read properties of undefined (reading 'indexOf')

The error message "Cannot read properties of undefined (reading 'indexOf')" usually occurs when you are trying to access a property or invoke a method on an undefined value. In this case, it seems like you are trying to reset fields using `this.$refs.formValidate.resetFields()`, but `formValidate` is undefined.

To fix this issue, make sure that you have defined `formValidate` and it is properly assigned to the form reference using `ref` attribute in your template. Here's an example of how you can define and use `formValidate`:

In your template:

<template>
  <el-form ref="formValidate" :model="formData" :rules="formRules">
    <!-- form fields -->
  </el-form>
</template>

In your component's script:

<script>
export default {
  data() {
    return {
      formData: {}, // initialize form data object
      formRules: {}, // define form validation rules
    }
  },
  methods: {
    resetForm() {
      // make sure that this.$refs.formValidate is defined
      if (this.$refs.formValidate) {
        this.$refs.formValidate.resetFields();
      }
    }
  },
}
</script>

By following this pattern, you should be able to resolve the error and reset the form fields successfully.