Azure functions dissapearing as soon as eventhubtrigger is added

Hi @Tijn SANDRA ,

Thanks for reaching out to Microsoft Q&A.

Your Python Functions host is failing to load once you add the Event Hub trigger so in the portal you see “no functions,” even though locally it works. That usually means there’s a startup exception (often a missing extension or package) that keeps the host from parsing your function.json files. Here’s what you can try:

1. Make sure you’ve pulled in the Event Hubs extension in Python
   • In your requirements.txt add:

           azure-functions-eventhub  
     

   • Run pip install -r requirements.txt, commit, and redeploy.
2. Configure extension bundles in host.json (Python v2+ model)

      host.json  
      {  
        "version": "2.0",  
        "extensionBundle": {  
      "id": "Microsoft.Azure.Functions.ExtensionBundle",  
      "version": "[3.*, 4.0.0)"  
        }  
      }  
   

3. Validate your app settings in Azure (portal → Configuration → Application settings)
   • FUNCTIONS_WORKER_RUNTIME = python
   • Your Event Hub connection string key matches the connection property in function.json
   • AzureWebJobsStorage is set to a valid Storage account connection
4. Check startup errors in real time
   • In the portal, go to Functions > Log stream or Platform features > Log stream
   • Look for exceptions under Host.Startup or messages about missing Python functions.
5. Verify your deployment model & file layout
   • If you ever created functions in the portal, that can overwrite your local wwwroot. Use the Kudu console (https://<your-app>.scm.azurewebsites.net) to confirm your function folders and host.json are present.
   • Avoid mixing portal-based edits with VS Code/git/zip deploy.
6. Restart the Function App after redeploying to force a fresh host startup.

If after those steps your functions still vanish, please share:

• Your host.json

• Your requirements.txt

• A snippet of the Log stream around the time of startup

That’ll help narrow down whether it’s still an extension-bundle issue or something else.

This sadly didn't solve my issue.

• Host.json:

{
  "version": "2.0",
  "logging": {
    "applicationInsights": {
      "samplingSettings": {
        "isEnabled": true,
        "excludedTypes": "Request"
      }
    }
  },
  "extensionBundle": {
    "id": "Microsoft.Azure.Functions.ExtensionBundle",
    "version": "[4.*, 5.0.0)"
  }
}

• Requirements.txt:

# Uncomment to enable Azure Monitor OpenTelemetry
# Ref: aka.ms/functions-azure-monitor-python
# azure-monitor-opentelemetry

azure-functions
azure-cosmos
azure-functions-worker
azure-eventhub
azure-functions-eventhub

• Log snippet (both at restart and at deploying):
  2026-05-07T13:59:57 [Verbose] Ping Status: { "hostState": "Running" }

2026-05-07T13:59:57   [Information]   Executing StatusCodeResult, setting HTTP status code 200
2026-05-07T14:00:36   [Verbose]   Ping Status: {   "hostState": "Running" }
2026-05-07T14:00:36   [Information]   Executing StatusCodeResult, setting HTTP status code 200
2026-05-07T14:00:42   [Verbose]   Initiating background SyncTriggers operation
2026-05-07T14:00:42   [Information]   Loading functions metadata
2026-05-07T14:00:42   [Information]   Reading functions metadata (Custom)
2026-05-07T14:00:42   [Information]   0 functions found (Custom)
2026-05-07T14:00:42   [Information]   0 functions loaded
2026-05-07T14:00:42   [Information]   Loading functions metadata
2026-05-07T14:00:42   [Information]   Reading functions metadata (Custom)
2026-05-07T14:00:42   [Information]   0 functions found (Custom)
2026-05-07T14:00:42   [Information]   0 functions loaded
2026-05-07T14:00:45   [Verbose]   Ping Status: {   "hostState": "Running" }
2026-05-07T14:00:45   [Information]   Executing StatusCodeResult, setting HTTP status code 200
2026-05-07T14:00:55   [Verbose]   Ping Status: {   "hostState": "Running" }
2026-05-07T14:00:55   [Information]   Executing StatusCodeResult, setting HTTP status code 200

Thanks for sharing the details. Have you checked if there are any exceptions in the logs=>run Exceptions query.

Nothing to see (if I'm doing it right)