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.

Portal Walkthrough¶

These portal blades help diagnose triggers not firing. All captures from a Consumption (Y1) Function App with PII masked.

Log Stream¶

[Observed] The Log stream blade shows real-time host startup and trigger listener initialization. Look for binding errors or missing connection warnings:

Log stream for trigger debugging

Diagnose and Solve Problems¶

[Observed] The Diagnose and solve problems blade provides automated detection of trigger and execution issues:

Diagnose and solve problems blade

Environment Variables¶

[Observed] The Environment variables blade shows connection strings and trigger configuration. Missing or incorrect values here are the most common cause of triggers not firing:

Environment variables blade

Logs (KQL Query Editor)¶

[Observed] The Logs blade provides direct KQL access to FunctionAppLogs and traces tables for diagnosing trigger listener failures:

Logs blade with KQL editor

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'"

CLI element	Explanation
Command(s)	`az account set`, `az monitor activity-log list`, `az rest`
Key flags	`--subscription`, `--resource-group`, `--offset`, `--max-events`, `--output`, `--method`, `--url`
Variables	`$SUBSCRIPTION_ID`, `$RG`, `$filter`
Expected result	Azure CLI applies the configuration change; confirm the returned JSON or follow-up query shows the expected value.

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

CLI element	Explanation
Command(s)	`az functionapp function list`, `az functionapp config appsettings list`
Key flags	`--name`, `--resource-group`, `--output`, `--query`
Variables	`$APP_NAME`, `$RG`
Expected result	Azure CLI applies the configuration change; confirm the returned JSON or follow-up query shows the expected value.

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

CLI element	Explanation
Command(s)	`az monitor metrics list`
Key flags	`--resource`, `--metric`, `--interval`, `--aggregation`, `--offset`, `--output`
Variables	`$SUBSCRIPTION_ID`, `$RG`, `$STORAGE_NAME`, `$EH_NAMESPACE`
Expected result	Azure CLI returns the requested resource data; verify names, IDs, status fields, or metric values match the scenario.

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

CLI element	Explanation
Command(s)	`az monitor activity-log list`, `az functionapp config appsettings list`
Key flags	`--resource-group`, `--offset`, `--status`, `--output`, `--name`
Variables	`$RG`, `$APP_NAME`
Expected result	Azure CLI applies the configuration change; confirm the returned JSON or follow-up query shows the expected value.

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

First 10 Minutes: Triggers Not Firing¶

Portal Walkthrough¶

Log Stream¶

Diagnose and Solve Problems¶

Environment Variables¶

Logs (KQL Query Editor)¶

Prerequisites¶

1) Check Azure status and regional incidents¶

Check in Portal¶

Check with Azure CLI¶

How to Read This¶

2) Check function enabled state¶

Check with Azure CLI¶

Example Output¶

How to Read This¶

3) Check trigger listener health¶

Check with KQL¶

Example Output¶

How to Read This¶

4) Check trigger source activity¶

Check with Azure CLI¶

How to Read This¶

5) Check recent deployments and configuration changes¶

How to Read This¶

Fast routing after triage¶

See Also¶

Sources¶