Update functions-troubleshoot-issues.md

Author: przlplx

support/azure/azure-functions/availability/functions-troubleshoot-issues.md

@@ -1,153 +1,154 @@
 ---
-title: Resolve Function App Down or Reporting Errors
-description: Describes how to troubleshoot the Azure Functions app if it's down or reporting errors.
+title: Resolve Function App Not Responding or Reporting Errors
+description: Describes how to troubleshoot Azure Functions app if it's not responding or reports errors.
 ms.date: 08/05/2025
 ms.reviewer: v-liuamson; v-gsitser
 ms.custom: sap:Function app down or reporting errors
 ---
 
-# Resolve Function App Down or Reporting Errors
+# Resolve function app not responding or reporting errors
 
 ## Common scenarios, error messages, and symptoms
 
-Function App failures typically fall into three major categories, which are configuration issues, customer code issues, and platform issues. This article explores these issues in detail and introduces the appropiate diagnostic tools for troubleshooting.
+Microsoft Azure Functions app failures typically fit into three major categories: configuration issues, customer code issues, and platform issues. This article explores these issues in detail and introduces the appropriate diagnostic tools for troubleshooting.
 
 ### Configuration issues
 
-These are the most frequent and include:
+These issues are the most common. They include:
 
-- Missing or incorrect application settings such as `AzureWebJobsStorage`, `FUNCTIONS_WORKER_RUNTIME`, or binding-specific configurations. For more info, check the [App settings reference for Azure Functions](/azure/azure-functions/functions-app-settings).
-- Storage account misconfigurations, including deleted accounts, rotated keys, or firewall restrictions. For more info, check the [Storage considerations for Azure Functions](/azure/azure-functions/storage-considerations?tabs=azure-cli).
-- Key Vault and Managed Identity access problems due to misconfigured permissions or missing identity assignments. Check the following resources for more info:
+- Missing or incorrect application settings, such as `AzureWebJobsStorage`, `FUNCTIONS_WORKER_RUNTIME`, and binding-specific configurations. For more information, see the [App settings reference for Azure Functions](/azure/azure-functions/functions-app-settings).
+- Storage account misconfigurations, including deleted accounts, rotated keys, and firewall restrictions. For more information, see [Storage considerations for Azure Functions](/azure/azure-functions/storage-considerations?tabs=azure-cli).
+- Key Vault and Managed Identity access problems because of misconfigured permissions or missing identity assignments. For more information, see the following resources:
   - [Use Key Vault references as app settings - Azure App Service](/azure/app-service/app-service-key-vault-references?tabs=azure-cli#troubleshoot-key-vault-references)
   - [Create a function app without default storage secrets in its definition - Azure Functions](/azure/azure-functions/functions-identity-based-connections-tutorial)
 
 ### Customer code issues
 
-These issues originate from:
+These issues have the following causes:
 
-- Faulty code patterns that lead to high CPU/memory usage, SNAT exhaustion, or runtime exceptions (e.g., division by zero, null reference).
-- Long-running or inefficient functions, which are especially problematic on consumption plans due to timeout constraints.
+- Faulty code patterns that cause high CPU or memory usage, SNAT exhaustion, or runtime exceptions (for example, division by zero or null reference).
+- Long-running or inefficient functions that are especially problematic on consumption plans because of timeout constraints.
 
-Check the following resources for more info:
+For more information, see the following resources:
 
 - [Azure Functions best practices](/azure/azure-functions/functions-best-practices?tabs=csharp)
 - [Improve Azure Functions performance and reliability](/azure/azure-functions/performance-reliability)
 - [Manage connections in Azure Functions](/azure/azure-functions/manage-connections?tabs=csharp)
 
 ### Platform issues
 
-Less frequent but impactful:
+These issues are less common but usually have a greater effect:
 
-- Unsupported runtime versions (e.g., Azure Functions `~2.x` or `~3.x`).
-Check the following resources for more info:
+- Unsupported runtime versions (for example, Azure Functions `~2.x` or `~3.x`).
+For more information, see the following resources:
   - [Azure Functions language stack support policy](/azure/azure-functions/language-support-policy?pivots=programming-language-csharp)
   - [Supported languages in Azure Functions](/azure/azure-functions/supported-languages?tabs=isolated-process%2Cv4&pivots=programming-language-csharp#languages-by-runtime-version)
 
-- Host startup failures, including placeholder site specialization errors or container allocation issues.
+- Host startup failures, including placeholder site specialization errors and container allocation issues.
 
 ### Typical error messages
 
-You may encounter common errors such as:
+You may experience common errors such as the following:
 
 - **Azure Functions runtime is unreachable.**
- [Troubleshoot error: Azure Functions runtime is unreachable](/azure/azure-functions/functions-recover-storage-account).
+
+    See [Troubleshoot error: Azure Functions runtime is unreachable](/azure/azure-functions/functions-recover-storage-account).
 
 - **Function host not running.**
 
 - **Access Denied**: `'C:\home\site\wwwroot\host.json'`.
 
-- **HTTP 5xx errors**: 503, 502, 500, or timeouts.
+- **HTTP 5*xx* errors**: 503, 502, 500, or timeouts.
 
-### Symptoms to watch
+### Symptoms to watch for
 
-- Function not triggering or executing. [Analyze Azure Functions telemetry in Application Insights](/azure/azure-functions/analyze-telemetry-data#viewing-telemetry-in-monitor-tab)
+- Function not triggering or running. See [Analyze Azure Functions telemetry in Application Insights](/azure/azure-functions/analyze-telemetry-data#viewing-telemetry-in-monitor-tab).
 
 - Missing invocation history or unexpected gaps.
 
-- High resource consumption (CPU/memory spikes flagged by detectors).
+- High resource consumption (CPU or memory spikes that are flagged by detectors).
 
-- Timeouts or long response times, especially on Consumption plans (max 230 seconds).
+- Timeouts or long response times, especially on Consumption plans (maximum of 230 seconds).
 
-- Functions not listed in the overview page.
+- Functions not listed on the overview page.
 
 ## Diagnostic tools
 
-You may use the following tools in the Azure portal to identify and resolve issues:
+To identify and resolve issues, you can use the following tools in the Azure portal.
 
 ### Function App Down or Reporting Errors (Preview)
 
 To access this tool, follow these steps:
 
 1. Sign in to the [Azure portal](https://portal.azure.com).
-1. Navigate to **Function App**.
+1. Open **Function App**.
 1. Select **Diagnose and solve problems**.
 1. Search for **Function App Down or Reporting Errors (Preview)**.
 
-**Features**:
+**Features of this tool**
 
-- Automates key troubleshooting checks using existing detectors.
+- Automates key troubleshooting checks by using existing detectors.
 - Provides minimal noise and focused root cause analysis.
-- Supports [Conversational diagnostics](https://techcommunity.microsoft.com/blog/appsonazureblog/power-of-conversational-diagnostics-public-preview-diagnostic-workflows/428866ution).
+- Supports [conversational diagnostics](https://techcommunity.microsoft.com/blog/appsonazureblog/power-of-conversational-diagnostics-public-preview-diagnostic-workflows/428866ution).
 
 ## Issue categories
 
-Function App downtime errors are classified into:
+Function app downtime errors are categorized as follows.
 
-### Common configuration problems
+### Common configuration issues
 
-- Misconfigured application settings.
-- Incorrect or unreachable storage account configuration.
-- Key Vault access permission issues.
-- Managed Identity authentication problems.
-- Binding/trigger misconfiguration.
-- Network connectivity issues.
+- Misconfigured application settings
+- Incorrect or unreachable storage account configuration
+- Key Vault access permission issues
+- Managed Identity authentication problems
+- Binding or trigger misconfiguration
+- Network connectivity issues
 
 ### Code and runtime resource issues
 
-- High CPU/memory consumption.
-- SNAT port exhaustion.
-- TCP connection exhaustion.
-- Long-running or stuck functions.
-- Runtime exceptions and failures.
-- Poor error handling or retry logic.
+- High CPU or memory consumption
+- SNAT port exhaustion
+- TCP connection exhaustion
+- Long-running or stuck functions
+- Runtime exceptions and failures
+- Poor error handling or retry logic
 
 ## Diagnostic checks performed
 
-The diagnostic workflow evaluates the following aspects of your Function App:
+The diagnostic workflow evaluates the following aspects of your function spp:
 
 - **General information**
-  - Hosting plan type (Consumption, Premium, Dedicated, Flex).
-  - Runtime version.
-  - Platform (Linux or Windows).
-  - Trigger types and bindings.
+  - Hosting plan type (Consumption, Premium, Dedicated, Flex)
+  - Runtime version
+  - Platform (Linux or Windows)
+  - Trigger types and bindings
 - **Startup issues**
-  - Diagnostic events during app startup.
-  - Offline history analysis for unexpected downtimes.
+  - Diagnostic events during app startup
+  - Offline history analysis for unexpected downtimes
 - **Recent deployments**
-  - Highlights deployments that may have impacted the app.
+  - Highlights deployments that may have impacted the app
 - **Runtime and language version validation**
-  - Confirms use of supported versions.
+  - Confirms use of supported versions
 - **Configuration checks**
-  - Verifies mandatory app settings.
-  - Validates Key Vault and Managed Identity configuration.
-  - Checks for SyncTrigger issues.
-  - Detects Function Host name collisions.
+  - Verifies mandatory app settings
+  - Verifies Key Vault and Managed Identity configuration
+  - Checks for SyncTrigger issues
+  - Detects Function Host name collisions
 - **Extension versions**
-  - Identifies outdated or unsupported extensions.
+  - Identifies outdated or unsupported extensions
 - **Hosting plan setup**
-  - Analyzes configuration and scaling behavior.
-  - Checks for SNAT port exhaustion, high CPU, and memory issues.
+  - Analyzes configuration and scaling behavior
+  - Checks for SNAT port exhaustion, high CPU, and memory issues
   - Includes risk alerts:
-    - For Dedicated plans: validates **AlwaysOn** is enabled.
-    - For Elastic Premium: checks VNet routing and scaling.
+    - For Dedicated plans: verifies that **AlwaysOn** is enabled
+    - For Elastic Premium: checks VNet routing and scaling
 - **Execution health**
   - Detects:
-    - Execution failures.
-    - Non-triggering functions.
-    - Stuck or long-running executions.
+    - Execution failures
+    - Non-triggering functions
+    - Stuck or long-running executions
 - **AI-powered analysis**
-  - Uses OpenAI to detect issue patterns and provide contextual recommendations.
+  - Uses OpenAI to detect issue patterns and provide contextual recommendations
 
 ### Application Insights queries
 
@@ -178,48 +179,48 @@ For diagnostics, run these queries in Application Insights:
     ```
 
 > [!NOTE]
-> Sampling is enabled by default. Disable temporarily if needed during investigation.
+> Sampling is enabled by default. If it's necessary, disable this feature temporarily during an investigation.
 
-For more info, check [Analyze Azure Functions telemetry in Application Insights](/azure/azure-functions/analyze-telemetry-data#viewing-telemetry-in-monitor-tab).
+For more information, see [Analyze Azure Functions telemetry in Application Insights](/azure/azure-functions/analyze-telemetry-data#viewing-telemetry-in-monitor-tab).
 
 ### Network validator tool
 
 > [!NOTE]
-> This applies to all hosting plans, with the exception of the Windows and Linux Consumption plans.
+> This tool applies to all hosting plans, except for the Windows and Linux Consumption plans.
 
-If your app shows errors such as `FAILED TO INITIALIZE RUN FROM PACKAGE.txt` or `host.json not found`, use the [Network troubleshooter](../../app-service/troubleshoot-vnet-integration-apps.md#network-troubleshooter) to resolve.
+If your app shows errors such as `FAILED TO INITIALIZE RUN FROM PACKAGE.txt` or `host.json not found`, use the [network troubleshooter](../../app-service/troubleshoot-vnet-integration-apps.md#network-troubleshooter) to resolve the errors.
 
-**To access:**
+To access the tool, follow these steps:
 
-- Log on to the [Azure portal](https://portal.azure.com).
-- Navigate to **Diagnose and solve problems**.
-- Search for **Connectivity Troubleshooter**.
+1. Sign in to the [Azure portal](https://portal.azure.com).
+1. Navigate to **Diagnose and solve problems**.
+1. Search for **Connectivity Troubleshooter**.
 
-**This tool checks for:**
+This tool checks for:
 
-- DNS resolution.
-- Storage and Key Vault access.
-- Outbound restrictions (VNet, NSG, firewalls).
+- DNS resolution
+- Storage and Key Vault access
+- Outbound restrictions (VNet, NSG, firewalls)
 
-**Ensure that:**
+When you use the network validator, make sure that:
 
 - VNet integration is correctly configured.
 - No endpoint or firewall blocks are in place.
 
-Check the following resources for more info:
+For more information, see the following resources:
 
 - [Azure Functions networking options](/azure/azure-functions/functions-networking-options?tabs=azure-portal#troubleshooting)
 - [Frequently asked questions about networking in Azure Functions](/azure/azure-functions/functions-networking-faq)
 
 ### Kudu logs (SCM)
 
 > [!NOTE]
-> This applies to all hosting plans, with the exception of the Linux Consumption and Flex Consumption plans.
+> This tool applies to all hosting plans, except for the Linux Consumption and Flex Consumption plans.
 
-Access logs under:
+### Additional logs
 
 - **Host Logs**: `%HOME%\LogFiles\Application\Functions\Host`
 - **Functions log**: `%HOME%\LogFiles\Application\Functions\Function\<your_triggername>`
 - **System-level log**: `%HOME%\LogFiles\Eventlog.xml`
 
-For more info, check [Understanding the Azure App Service file system](https://github.com/projectkudu/kudu/wiki/understanding-the-azure-app-service-file-system).
+For more information, see [Understanding the Azure App Service file system](https://github.com/projectkudu/kudu/wiki/understanding-the-azure-app-service-file-system).