https://docs.microsoft.com/en-us/azure/azure-functions/functions-reference-python
To access Azure blob (container) storage my variable MyStorageConnectionAppSetting must be set. Otherwise you'll see this error.
System.Private.CoreLib: Exception while executing function: Functions.uploadTest. Microsoft.Azure.WebJobs.Host: Storage account connection string 'AzureWebJobsMyStorageConnectionAppSetting' does not exist. Make sure that it is a defined App Setting.
See https://docs.microsoft.com/en-us/azure/static-web-apps/application-settings for details.
Note that for the deployed app the value must be set in the Azure Portal, and for local testing set in local.settings.json.