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First 10 Minutes: Triggers Not Firing

When functions are not executing despite active trigger sources, use this checklist to narrow down the cause within the first 10 minutes.

Prerequisites

  • Azure CLI access to the production subscription.
  • Access to Application Insights and Log Analytics.
  • Health endpoint implemented at GET /api/health.

Set shared variables:

RG="rg-myapp-prod"
APP_NAME="func-myapp-prod"
SUBSCRIPTION_ID="<subscription-id>"
APP_INSIGHTS_NAME="appi-myapp-prod"
WORKSPACE_ID="xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx"
STORAGE_NAME="stmyappprod"
EH_NAMESPACE="evh-myapp-prod"

flowchart TD
    A[Trigger not firing] --> B["Check platform/regional incidents"]
    B --> C[Check function enabled state]
    C --> D{Enabled?}
    D -->|No| E["Re-enable function/app setting"]
    D -->|Yes| F[Check listener startup traces]
    F --> G{Listener healthy?}
    G -->|No| H["Fix auth/config startup issue"]
    G -->|Yes| I[Check source activity and publisher]

1) Check Azure status and regional incidents

Rule out platform-wide issues first.

Check in Portal

Azure portal → Service Health → Health advisories.

Filter for the production region and services: Azure Functions, Storage, Azure Monitor.

Check with Azure CLI

az account set --subscription "$SUBSCRIPTION_ID"
az monitor activity-log list \
  --subscription "$SUBSCRIPTION_ID" \
  --resource-group "$RG" \
  --offset 1h \
  --max-events 20 \
  --output table

az rest --method get \
  --url "https://management.azure.com/subscriptions/$SUBSCRIPTION_ID/providers/Microsoft.ResourceHealth/events?api-version=2022-10-01&\$filter=eventType eq 'ServiceIssue' and status eq 'Active'"

How to Read This

Signal Interpretation Action
No platform-originated events Likely app/dependency/local change Continue to Step 2
Microsoft.Web/sites/Restarted + Cause=Platform Platform event, not app deploy Track Service Health advisory
Multiple infrastructure operations in same window Possible platform turbulence Correlate with regional advisories

2) Check function enabled state

The most common (and most overlooked) cause of zero invocations is a disabled function.

Check with Azure CLI

az functionapp function list \
  --name "$APP_NAME" \
  --resource-group "$RG" \
  --output table

az functionapp config appsettings list \
  --name "$APP_NAME" \
  --resource-group "$RG" \
  --query "[?contains(name, 'AzureWebJobs') || contains(name, 'DISABLE')]" \
  --output table

Example Output

Name             Trigger    IsDisabled
---------------  ---------  ----------
QueueProcessor   queue      true
health           http       false

Name                                 Value
-----------------------------------  ----------
AzureWebJobs.QueueProcessor.Disabled true

How to Read This

Signal Interpretation Action
IsDisabled = true Function explicitly disabled Remove disable setting and restart
AzureWebJobs.<FunctionName>.Disabled = true App setting disabling function Delete the app setting
All functions enabled Cause is not disable state Continue to Step 3

3) Check trigger listener health

Verify that trigger listeners started successfully after the most recent host startup.

Check with KQL

let appName = "func-myapp-prod";
traces
| where timestamp > ago(30m)
| where cloud_RoleName =~ appName
| where message has_any ("listener", "Host started", "unable to start", "trigger", "Starting Host")
| project timestamp, severityLevel, message
| order by timestamp desc

Example Output

# Healthy
timestamp                    message
---------------------------  ----------------------------------------------
2026-04-04T11:32:26Z         Host started (64ms)
2026-04-04T11:32:26Z         Job host started
2026-04-04T11:32:26Z         Listener started for function 'QueueProcessor'

# Unhealthy
timestamp                    message
---------------------------  ----------------------------------------------
2026-04-04T11:32:26Z         Starting Host (HostId=func-myapp-prod)
2026-04-04T11:32:46Z         Listener for function 'QueueProcessor' was unable to start
2026-04-04T11:32:46Z         The listener for function 'QueueProcessor' was unable to start. Azure.Storage: 403

How to Read This

Signal Interpretation Action
Listener started present Trigger listener healthy Check source-side activity
unable to start with 403 Storage auth failure Check managed identity and RBAC
No listener messages at all Host may not have completed startup Check host lifecycle logs

4) Check trigger source activity

Confirm events are actually arriving at the trigger source.

Check with Azure CLI

# Queue trigger: check queue message count
az monitor metrics list \
  --resource "/subscriptions/$SUBSCRIPTION_ID/resourceGroups/$RG/providers/Microsoft.Storage/storageAccounts/$STORAGE_NAME" \
  --metric "QueueMessageCount" \
  --interval PT1M \
  --aggregation Average \
  --offset 30m \
  --output table

# Event Hub trigger: check incoming messages
az monitor metrics list \
  --resource "/subscriptions/$SUBSCRIPTION_ID/resourceGroups/$RG/providers/Microsoft.EventHub/namespaces/$EH_NAMESPACE" \
  --metric "IncomingMessages" \
  --interval PT1M \
  --aggregation Total \
  --offset 30m \
  --output table

How to Read This

Signal Interpretation Action
Messages present in source Source is active, function should be processing Listener or host issue
Zero messages in source No work to process Investigate upstream publisher
Blob trigger with no Event Grid subscription FC1 blob trigger requires Event Grid Create Event Grid subscription

5) Check recent deployments and configuration changes

az monitor activity-log list \
  --resource-group "$RG" \
  --offset 2h \
  --status Succeeded \
  --output table

az functionapp config appsettings list \
  --name "$APP_NAME" \
  --resource-group "$RG" \
  --output table

How to Read This

Signal Interpretation Action
Deploy/config change immediately before failure High-confidence regression candidate Prepare rollback
No change events in incident window Runtime/dependency/platform cause Continue deeper investigation
FUNCTIONS_WORKER_RUNTIME changed or missing Function discovery will fail Restore correct runtime value

Fast routing after triage

What you see Likely area Next action
Function disabled Configuration Re-enable and verify
Listener failed to start Auth/connection Use Managed Identity / RBAC Failure playbook
Source has no events Upstream publisher Investigate publisher and subscription
Host not starting Startup/config Use App Settings Misconfiguration playbook
Recent deploy correlates Regression Roll back, then follow Methodology

See Also

Sources