# Check App Service slots when Profiler sessions compete for the same VM

> Account for running deployment slots in a profiling-contention investigation.

- Canonical URL: https://update.dsesecurity.com/updates/dse-20260917-010-check-app-service-slots-when-profiler-sessions-compete-for-the-same-vm/
- Publisher: Detection Systems & Engineering (DSE Security)
- Author: DSE Security Editorial Team
- Published: 2026-09-17T16:34:50+00:00
- Modified: 2026-09-17T16:35:03+00:00
- Last reviewed by DSE: 2026-09-17
- Resource type: Guide
- DSE priority: Information
- Topics: Cybersecurity, IT
- Reading time: 1 minutes

## What you need to know

Account for running deployment slots in a profiling-contention investigation.

## Potentially affected

Use this review after observing the documented profiling-session problem. Identify the applications, running slots and App Service plans involved, together with the deployment schedule. This diagnosis does not establish that every missing profile is caused by session contention.

## DSE recommendation

DSE recommends inventorying slot use with the application owners before changing profiling.

## Article

## Source facts

For too many active Application Insights profiling sessions, Microsoft identifies running deployment slots as participants that compete for a profiling session on their VM. Its remedies include stopping unused slots, disabling unnecessary profiling and moving applications between App Service plans. It also discusses staging-slot profiling during deployments. [Microsoft Learn](https://learn.microsoft.com/en-us/azure/azure-monitor/profiler/profiler-troubleshooting).

## Applicability

Use this review after observing the documented profiling-session problem. Identify the applications, running slots and App Service plans involved, together with the deployment schedule. This diagnosis does not establish that every missing profile is caused by session contention.

## DSE recommendation

DSE recommends inventorying slot use with the application owners before changing profiling. Choose the smallest approved adjustment that tests the contention explanation. Do not stop a slot merely because it is labeled staging; confirm its current purpose and preserve its previous state. Schedule any test around active releases and retain a reversal plan.

## Verification

Record the initial error and the applications sharing the affected arrangement. Apply the approved adjustment, request a bounded profiling session and confirm whether a usable trace appears. Repeat the relevant deployment case if it caused the original symptom. Restore required slot behavior and document whether the evidence supports contention or requires another diagnostic branch.

## Official references

[Microsoft Learn: Troubleshoot the .NET Profiler](https://learn.microsoft.com/en-us/azure/azure-monitor/profiler/profiler-troubleshooting).

## Primary reference

- Name: Troubleshoot the .NET Profiler - Azure Monitor | Microsoft Learn
- Authority: Microsoft Learn
- URL: https://learn.microsoft.com/en-us/azure/azure-monitor/profiler/profiler-troubleshooting
- Source publication date: Not stated by the source

## Citation and use

Preferred citation: “Check App Service slots when Profiler sessions compete for the same VM,” DSE Security, https://update.dsesecurity.com/updates/dse-20260917-010-check-app-service-slots-when-profiler-sessions-compete-for-the-same-vm/
Publishing principles: https://update.dsesecurity.com/updates/dse-updates-editorial-methodology/
Usage and citation policy: https://update.dsesecurity.com/usage/
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