Known regression: Activity input fails to deserialize when the input is an array

[bachuv]

Known regression notice: Activity input fails to deserialize when the input is an array

Error description:
We have just noticed that some users are experiencing errors in Durable Functions Python apps with an exception that includes Exception binding parameter '<your activity parameter name>' and Unexpected character encountered while parsing value.

This issue started with Durable Functions version v2.13.0. The following extension bundles are affected:

• v4 bundles: 4.13.1
• v3 bundles: 3.30.1+

Repro:
Use an array type as an input to your activity function.

# An HTTP-Triggered Function with a Durable Functions Client binding
@myApp.route(route="orchestrators/{functionName}")
@myApp.durable_client_input(client_name="client")
async def http_start(req: func.HttpRequest, client):
    function_name = req.route_params.get('functionName')
    instance_id = await client.start_new(function_name)
    response = client.create_check_status_response(req, instance_id)
    return response

# Orchestrator
@myApp.orchestration_trigger(context_name="context")
def hello_orchestrator(context):
    cities = ["Tokyo", "Seattle", "Cairo"]
    results = yield context.call_activity("hello", cities)
    return results

# Activity
@myApp.activity_trigger(input_name="cities")
def hello(cities: list):
    results = []
    for city in cities:
        result = f"Hello {city}"
        context.log(result)
        results.append(result)
    return results

Incoming solution:
We're issuing a hotfix extension bundles release that will automatically fix any apps that are hitting the issue described here. It will take a few days to roll out.

Immediate Mitigation Options:
There are two ways to fix this issue: Pinning the extension bundles version or manually installing the working Durable Functions extension version.

1. Pinning the extension bundles version - Update the extension bundles version in host.json to use v3.29.0 or v4.12.0.

Example:

  "extensionBundle": {
    "id": "Microsoft.Azure.Functions.ExtensionBundle",
    "version": "[4.*, 4.13.0)"
  },

2. Manually install Durable Functions extension version v2.12.0 or lower by following these instructions.