Azure App Service Plan CPU and Memory metrics stopped reporting since Sep 30, 2026, but application is still running

Environment

Azure Region: East Asia

Project Name: ProductionProject

App Service: ProductionWebApp

App Service Plan: ProductionAppServicePlan

Resource Group: ProductionResourceGroup

Operating System: Windows

Pricing Tier: Basic B1 (1 instance)

Application: ASP.NET Core 6

Only one App Service is hosted on this App Service Plan.

Problem Description

Since approximately September 30, 2026, Azure Monitor has suddenly stopped reporting CPU and memory metrics for our production Azure App Service and its App Service Plan.

The application remains accessible and operational, but some customers have reported intermittent slowness.

All metrics were reporting normally before September 30.

Symptoms

App Service CPU Time continuously shows 0 seconds.

App Service Data In shows no data.

App Service Plan CPU Percentage and Memory Percentage no longer report valid values.

Azure Portal displays missing metric data after approximately September 30.

Restarting the App Service did not resolve the issue.

Another App Service running on a separate Linux B1 App Service Plan in the same Azure region continues reporting metrics normally.

Azure CLI Verification

We queried the same App Service Plan using Azure CLI.

September 27, 2026 — Metrics working correctly

CPU Percentage:

[
  {"timeStamp": "2026-09-27T00:00:00Z", "average": 8.3167},
  {"timeStamp": "2026-09-27T01:00:00Z", "average": 5.0778}
]

Memory Percentage:

[
  {"timeStamp": "2026-09-27T00:00:00Z", "average": 77.925},
  {"timeStamp": "2026-09-27T01:00:00Z", "average": 78.2194}
]

October 11, 2026 — Metrics missing

Both CPU Percentage and Memory Percentage return timestamps without any average values:

[
  {"timeStamp": "2026-10-11T00:00:00Z"},
  {"timeStamp": "2026-10-11T01:00:00Z"}
]

The Azure Monitor API requests complete successfully, but no metric values are returned.

This confirms that the issue is not limited to the Azure Portal chart visualization.

Troubleshooting Already Performed

Confirmed that the App Service is running and accessible.

Verified that the App Service Plan contains only one application.

Restarted the App Service, but the issue persists.

Compared Azure Monitor metrics before and after September 30.

Confirmed missing CPU and memory values using Azure CLI.

Verified that another App Service Plan in the same region reports metrics normally.

Questions

Could this indicate that the underlying App Service worker has stopped publishing platform metrics?

Could this be an Azure Monitor metrics collection or ingestion issue?

Were there any known platform maintenance events or telemetry-related changes in East Asia around September 30, 2026?

Is there a way to restore metric reporting without recreating or migrating the production App Service Plan?

Could this issue be related to the intermittent performance degradation reported by some customers?

We would appreciate any guidance on how to diagnose and resolve this issue while minimizing downtime for our production application.

Thank you.

Environment

Azure Region: East Asia

Project Name: ProductionProject

App Service: ProductionWebApp

App Service Plan: ProductionAppServicePlan

Resource Group: ProductionResourceGroup

Operating System: Windows

Pricing Tier: Basic B1 (1 instance)

Application: ASP.NET Core 6

Only one App Service is hosted on this App Service Plan.

Problem Description

Since approximately September 30, 2026, Azure Monitor has suddenly stopped reporting CPU and memory metrics for our production Azure App Service and its App Service Plan.

The application remains accessible and operational, but some customers have reported intermittent slowness.

All metrics were reporting normally before September 30.

Symptoms

App Service CPU Time continuously shows 0 seconds.

App Service Data In shows no data.

App Service Plan CPU Percentage and Memory Percentage no longer report valid values.

Azure Portal displays missing metric data after approximately September 30.

Restarting the App Service did not resolve the issue.

Another App Service running on a separate Linux B1 App Service Plan in the same Azure region continues reporting metrics normally.

Azure CLI Verification

We queried the same App Service Plan using Azure CLI.

September 27, 2026 — Metrics working correctly

CPU Percentage:

[
  {"timeStamp": "2026-09-27T00:00:00Z", "average": 8.3167},
  {"timeStamp": "2026-09-27T01:00:00Z", "average": 5.0778}
]

Memory Percentage:

[
  {"timeStamp": "2026-09-27T00:00:00Z", "average": 77.925},
  {"timeStamp": "2026-09-27T01:00:00Z", "average": 78.2194}
]

October 11, 2026 — Metrics missing

Both CPU Percentage and Memory Percentage return timestamps without any average values:

[
  {"timeStamp": "2026-10-11T00:00:00Z"},
  {"timeStamp": "2026-10-11T01:00:00Z"}
]

The Azure Monitor API requests complete successfully, but no metric values are returned.

This confirms that the issue is not limited to the Azure Portal chart visualization.

Troubleshooting Already Performed

Confirmed that the App Service is running and accessible.

Verified that the App Service Plan contains only one application.

Restarted the App Service, but the issue persists.

Compared Azure Monitor metrics before and after September 30.

Confirmed missing CPU and memory values using Azure CLI.

Verified that another App Service Plan in the same region reports metrics normally.

Questions

Could this indicate that the underlying App Service worker has stopped publishing platform metrics?

Could this be an Azure Monitor metrics collection or ingestion issue?

Were there any known platform maintenance events or telemetry-related changes in East Asia around September 30, 2026?

Is there a way to restore metric reporting without recreating or migrating the production App Service Plan?

Could this issue be related to the intermittent performance degradation reported by some customers?

We would appreciate any guidance on how to diagnose and resolve this issue while minimizing downtime for our production application.

Thank you.