##[error]Error: Error: Failed to deploy web package to App Service. Conflict (CODE: 409)

I've been trying to deploy my FastAPI application on Azure DevOps for the past two days. It was working perfectly before, but now it's not working even though I haven't made any changes to the pipeline.

My Pipeline is:

trigger:
- main

variables:
  azureServiceConnectionId: service_connectionID
  webAppName: appname
  vmImageName: 'image'
  environmentName: 'env'
  projectRoot: $(System.DefaultWorkingDirectory)
  pythonVersion: '3.11'

stages:
- stage: Build
  displayName: Build stage
  jobs:
  - job: BuildJob
    pool:
      vmImage: $(vmImageName)
    steps:
    # Set up Python environment
    - task: UsePythonVersion@0
      inputs:
        versionSpec: '$(pythonVersion)'
      displayName: 'Use Python $(pythonVersion)'

    # Install dependencies
    - script: |
        python -m venv antenv
        source antenv/bin/activate
        python -m pip install --upgrade pip
        pip install setuptools wheel
        pip install -r requirements.txt
      workingDirectory: $(projectRoot)
      displayName: 'Install requirements'
      
    # Create deployment package
    - task: ArchiveFiles@2
      displayName: 'Archive files'
      inputs:
        rootFolderOrFile: '$(projectRoot)'
        includeRootFolder: false
        archiveType: zip
        archiveFile: $(Build.ArtifactStagingDirectory)/$(Build.BuildId).zip
        replaceExistingArchive: true

    # Publish build artifacts
    - task: PublishBuildArtifacts@1
      inputs:
        PathtoPublish: '$(Build.ArtifactStagingDirectory)'
        ArtifactName: 'drop'
        publishLocation: 'Container'

- stage: Deploy
  displayName: 'Deploy Web App'
  dependsOn: Build
  condition: succeeded()
  jobs:
  - deployment: DeploymentJob
    environment: $(environmentName)
    pool:
      vmImage: $(vmImageName)
    strategy:
      runOnce:
        deploy:
          steps:
          # Deploy the web app
          - task: AzureWebApp@1
            displayName: 'Deploy Azure Web App'
            inputs:
              azureSubscription: $(azureServiceConnectionId)
              appType: 'webAppLinux'
              appName: $(webAppName)
              package: '$(Pipeline.Workspace)/drop/$(Build.BuildId).zip'
              runtimeStack: 'PYTHON|3.11'
              startUpCommand: 'startup.txt'
              deploymentMethod: 'auto'

My startup command is :

gunicorn -w 4 -k uvicorn.workers.UvicornWorker --timeout 600 -b 0.0.0.0:8000 app:app

and its giving me error as

##[error]Failed to deploy web package to App Service.

##[warning]Can't find loc string for key: KuduStackTraceURL

##[error]KuduStackTraceURL https://:@ai-commission-dsbfcbduhcb6gtfz.scm.eastus2-01.azurewebsites.net/api/vfs/LogFiles/kudu/trace

##[error]Error: Error: Failed to deploy web package to App Service. Conflict (CODE: 409)

##[warning]Error: Failed to update deployment history. Error: Bad Request (CODE: 400)

You can try with the following things:

1. Restart the web app.

2. Check the app service plan used by your Azure Web App, ensure the web app has not reached to the limitation of the plan.

   • If you are using a free plan, the resources (such as CPU, memory, etc..) provided by this plan are quite limited. When the available resources are not enough or the limitation is reached, the deployment could be failed. At this time, you need to pay for a higher plan to get more available resources.
   • If you have paid for a plan, scale up to a higher plan to get more available resources.