Azure Application Insights is not receiving telemetry from local

Question

Azure Application Insights is not receiving telemetry from local

Maria Natalia Benavides Sanabria 10

Azure Application Insights was configured in two backend services running locally, one in Node.js and the other in Python. However, no telemetry is being displayed in Azure Portal. No data appears in tables such as traces, requests, dependencies, or customEvents.

The connection string is configured through environment variables and is successfully validated at application startup. The Application Insights resource is enabled in Azure, and the user has the required access role on the resource.

Environment

ComponentDetailNode.jsv24.13.0----------------Node.jsv24.13.0TypeScript^5.3.2Python3.12.0Operating systemWindows 11 (local)Node.js SDK installed@azure/monitor-opentelemetry@1.16.0Python SDKazure-monitor-opentelemetry## Current implementation

Node.js

Telemetry is initialized at application startup using the following implementation:

import * as appInsights from 'applicationinsights';

export function initTelemetry(connectionString: string | undefined): void {
    if (!connectionString) {
        console.warn('[Telemetry] Connection string is not defined. Telemetry disabled.');
        return;
    }

    appInsights
        .setup(connectionString)
        .setAutoDependencyCorrelation(true)
        .setAutoCollectRequests(true)
        .setAutoCollectPerformance(true)
        .setAutoCollectExceptions(true)
        .setAutoCollectDependencies(true)
        .setAutoCollectConsole(true, true)
        .setUseDiskRetryCaching(true)
        .setSendLiveMetrics(true)
        .start();

    appInsights.defaultClient.trackEvent({
        name: 'AppStartup',
        properties: { 'telemetry.startup': 'true' }
    });
}

Telemetry is initialized before the rest of the application starts.

Python

Azure Monitor is configured at startup using configure_azure_monitor, and custom events are sent through logging.

Environment variable

APPLICATIONINSIGHTS_CONNECTION_STRING=InstrumentationKey=...;IngestionEndpoint=...;...

Current Azure status

Application Insights resource is enabled
Local application is enabled in the resource
User role assigned: Monitoring Metrics Publisher

Suchitra Suregaunkar 12,100 Reputation points Microsoft External Staff Moderator

2026-03-30T20:16:34.27+00:00
Hello Maria Natalia Benavides Sanabria

Thank you for posting your query on Microsoft Q&A portal and sharing the full context and implementation details. Based on your setup (local Node.js + Python apps, Windows 11, OpenTelemetry–based SDKs, validated connection string, but zero data in all Application Insights tables).

You are mixing two different telemetry pipelines that are not compatible as currently implemented

Node.js

You are initializing telemetry using the legacy applicationinsights SDK

At the same time, your environment uses OpenTelemetry-based packages (@azure/monitor-opentelemetry)

Python

Uses Azure Monitor OpenTelemetry Distro (azure-monitor-opentelemetry)

Azure Monitor Application Insights must be instrumented consistently using OpenTelemetry when using the Azure Monitor OpenTelemetry Distro. Mixing legacy SDKs and OpenTelemetry SDKs is not supported and can result in telemetry being dropped silently.

Reference: https://learn.microsoft.com/en-us/azure/azure-monitor/app/opentelemetry-enable?tabs=aspnetcore

Below are the reasons for Telemetry Not Appearing Even Though Setup Looks Correct:

Legacy SDK vs OpenTelemetry conflict (Node.js):

Your Node.js code uses:

import * as appInsights from 'applicationinsights';

However:

applicationinsights v3.x is OpenTelemetry-based

@azure/monitor-opentelemetry is also OpenTelemetry-based

Running both pipelines causes duplicate exporters and span processors

Result: telemetry never reaches ingestion

Microsoft explicitly warns to use only one OpenTelemetry entry point per application.

Unsupported Node.js runtime: You are running node.js v24.13.0 but Azure Monitor OpenTelemetry does not yet support Node.js 24. Supported versions are only those officially supported by OpenTelemetry.

Running on an unsupported runtime results in no exporter initialization, with no visible errors.

Python: traces may exist but not export without active instrumentation

In Python: configure_azure_monitor(connection_string=...)

The Azure Monitor OpenTelemetry Python distro does not automatically instrument everything

A tracer span alone may not appear unless:

Requests / frameworks (Flask, FastAPI, etc.) are instrumented

OR logging is correctly bridged to OpenTelemetry

Reference: https://learn.microsoft.com/en-us/python/api/overview/azure/monitor-opentelemetry-readme?view=azure-python

Local outbound connectivity to ingestion endpoints:

When running locally on Windows:

Telemetry is sent over HTTPS to:

{region}.in.applicationinsights.azure.com

dc.services.visualstudio.com

If outbound HTTPS (443) is blocked by:

Corporate firewall

VPN

Endpoint security software

Telemetry is silently dropped.

Please look into below workaround:

Do not use the applicationinsights SDK.

Use only Azure Monitor OpenTelemetry:
import { useAzureMonitor } from "@azure/monitor-opentelemetry"; useAzureMonitor({ connectionString: process.env.APPLICATIONINSIGHTS_CONNECTION_STRING, });

Remove:

applicationinsights

setup()

defaultClient.trackEvent

Use a supported Node.js version: v18 or v20 (LTS).

Ensure telemetry is actually generated:

Use a supported framework (Flask, FastAPI, requests), or

Create spans after calling configure_azure_monitor().

Use the standard logging module (not print).

Outbound HTTPS (443) must be allowed to:

dc.services.visualstudio.com

{region}.in.applicationinsights.azure.com

Role assigned: Monitoring Metrics Publisher is Sufficient and Not required to send telemetry

Telemetry ingestion does not depend on RBAC.

Thanks,

Suchitra.
Suchitra Suregaunkar 12,100 Reputation points Microsoft External Staff Moderator

2026-04-01T19:27:31.22+00:00

Hello Maria Natalia Benavides Sanabria

Could you please let us know if the comment above resolved your issue? If you need any further assistance, feel free to reach out, we're always here to support you.

If you found the comment helpful, please consider clicking "Upvote it."

Thanks,

Suchitra.
Maria Natalia Benavides Sanabria 10 Reputation points

2026-04-10T00:20:24.8333333+00:00

Hello @Suchitra Suregaunkar ,

Thank you for your follow-up.

The issue has not been resolved yet. The telemetry information is still not reaching Azure Application Insights, so no data is being ingested or reflected there.
Suchitra Suregaunkar 12,100 Reputation points Microsoft External Staff Moderator

2026-04-10T10:32:56.8033333+00:00
Hello Maria Natalia Benavides Sanabria

Even when the Application Insights SDK is correctly configured and telemetry is being generated locally, ingestion can still fail if there is an issue in the telemetry processing pipeline.

If telemetry does not appear in the Azure portal, the following conditions may apply:

The SDK is correctly configured, but outbound network connectivity to the ingestion endpoint is blocked.

The ingestion endpoint may reject inbound telemetry due to authentication mismatch (for example, if Microsoft Entra ID–based ingestion is enabled on the Application Insights resource).

DNS resolution failures, firewall restrictions, or proxy settings in the local environment may prevent telemetry from reaching the ingestion endpoint.

In such scenarios, telemetry is silently rejected and does not appear in the Azure portal even though the application is generating telemetry data locally.

As a next step, it is recommended to test direct telemetry ingestion using a sample request (via PowerShell or curl) to determine whether the issue is related to SDK instrumentation or network/ingestion endpoint connectivity.

Reference: https://learn.microsoft.com/en-us/troubleshoot/azure/azure-monitor/app-insights/telemetry/investigate-missing-telemetry?tabs=net#steps-that-can-cause-telemetry-to-be-missing

Thanks,
Suchitra.