Deploy to AzureDevOps - Error: Failed to get App service 'xxx' application settings - azure

Question

I want to deploy a Static Web App. Build and deploy stages are specified in azure-pipeline. The pipeline fails when it comes to AzureAppServiceSettings#1 task. That is what I got in log:
Got service connection details for Azure App Service:'xxx-dev-app'
Trying to update App Service Application settings. Data: {"testDb":"test"}
##[error]Error: Failed to get App service 'xxx-dev-app' application settings. Error: The Resource 'Microsoft.Web/sites/xxx-dev-app' under resource group 'xxx-dev-rg' was not found.
The task in azure-pipeline is:
- task: AzureAppServiceSettings#1
displayName: Azure App Service Settings
inputs:
azureSubscription: 'ServiceConnectionName'
appName: 'xxx-dev-app'
resourceGroupName: 'xxx-dev-rg'
appSettings: |
[
{
"name": "testDb",
"value": "test",
"slotSetting": false
}
]
DevOps has a Contributor access level both in the app and resource group.
Any suggestions what causes deployment failure?

Answer 1

I added a task for artifact downloading as it was proposed by #Daniel Mann, and it worked:
trigger:
- master
pool:
vmImage: ubuntu-latest
variables:
buildConfiguration: 'Release'
stages:
- stage: Build
jobs:
- job: Build
displayName: 'Build'
steps:
- task: DotNetCoreCLI#2
inputs:
command: 'build'
configuration: 'Release'
arguments: --output $(System.DefaultWorkingDirectory)/publish_output --configuration $(buildConfiguration)
- task: ArchiveFiles#2
displayName: 'Archive files'
inputs:
rootFolderOrFile: '$(System.DefaultWorkingDirectory)/publish_output'
includeRootFolder: false
archiveType: zip
archiveFile: $(Build.ArtifactStagingDirectory)/$(Build.BuildId).zip
replaceExistingArchive: true
- publish: $(Build.ArtifactStagingDirectory)/$(Build.BuildId).zip
artifact: drop
- stage: Test
dependsOn: Build
condition: succeeded()
jobs:
- job: Deploy
displayName: 'Deploy to Test'
steps:
- download: current
artifact: drop
- task: AzureWebApp#1
inputs:
azureSubscription: 'yyy'
appType: 'webApp'
appName: 'xxx'
package: '$(Pipeline.Workspace)/drop/*.zip'