Failed to find a default file in the app artifacts folder (/). Valid default files: index.html,Index.html

Hi,

I'm running a static website on WordPress hosted on a Linux VM. Now I want to migrate to WordPress site to Azure Static Web App.
I have created a repo in Azure DevOps and pushed WordPress code to the repo. Created pipeline to deploy the code in Azure static web app but got below mentioned error.

Yaml file:-

trigger:
- main

pool:
vmImage: ubuntu-latest

steps:
- task: AzureStaticWebApp@0
displayName: 'Static Web App: '
inputs:
workingDirectory: '$(System.DefaultWorkingDirectory)/_Principle'
skip_app_build: true
skip_api_build: false
is_static_export: false
verbose: false
azure_static_web_apps_api_token: '$(token)'

**Error:-**
deployment configuration file points to the root of your application.
2023-09-01T09:47:39.5459574Z ##[error]If your application requires build steps, please validate that a default file exists in the build output directory.
2023-09-01T09:47:39.5459772Z ##[error]
2023-09-01T09:47:39.5936184Z
2023-09-01T09:47:39.5937181Z ##[warning]For further information, please visit the Azure Static Web Apps documentation at https://docs.microsoft.com/en-us/azure/static-web-apps/
2023-09-01T09:47:39.5937680Z ##[warning]If you believe this behavior

is unexpected, please raise a GitHub issue at https://github.com/azure/static-web-apps/issues/
2023-09-01T09:47:39.5937940Z ##[warning]Exiting
2023-09-01T09:47:39.7344388Z ##[error]Error: The process '/usr/bin/bash' failed with exit code 1
2023-09-01T09:47:39.7444178Z ##[section]Finishing: Static Web App: