Azure function - OS: Linux, plan Flex Consumption, Diagnostic tool is not working

Question

Hello,

We have azure function on Linux with plan Flex Consumption. When I'm traying to open Diagnostic Tool there is only error Sorry, an error occurred. Please refresh the page and try again.

Did you face such a problem?

Answer 1

Hi @Tomasz Pycia ,

Thanks for reaching out to Microsoft Q&A.

Azure Functions running on Linux with the Elastic/Flexible Consumption plan do not fully support some portal diagnostic features, including the Diagnostic Tool and certain log streaming capabilities. This is because the underlying sandbox environment on Linux hosts in this plan is more restricted compared to Windows or Premium plans.

The portal tries to load diagnostic information via Kudu/SCM APIs, which are either limited or not fully available for Linux in Flex Consumption. Hence, you just see a generic “Sorry, an error occurred” message.

Here are a few workarounds to get the same kind of insights:

1. Diagnostics for Flex Consumption apps are accessed through the “Diagnose and solve problems” blade in the Function App:
   • Open your Function App in the Azure portal=>Select Diagnose and solve problems from the left-hand menu.
   • Use one of the supported workflows for Flex Consumption apps:
   • Function App Down or Reporting Errors (Preview): Checks startup, runtime, configuration, and execution health issues.
   • Flex Consumption Deployment: Reviews deployment history, package status, and related recommendations.
   • Flex Consumption Quota: Monitors regional subscription memory/core usage and related quotas.
2. Enable Application Insights
   • Make sure you’ve set APPLICATIONINSIGHTS_CONNECTION_STRING (or APPINSIGHTS_INSTRUMENTATIONKEY) in your Function App settings.
   • Use the Logs (Analytics) blade in the portal to run Kusto queries (requests, traces, exceptions) against your function.
3. Use Azure Monitor Metrics Explorer
   • In Flex Consumption on Linux you get the FunctionsExecutionCount and FunctionsExecutionUnits metrics.
   • Open Metrics Explorer in Azure Monitor to chart those metrics over time.
4. Stream logs in real time
   • In the portal go to your Function App > Streaming logs (Platform features > Log stream).
   • Or from your dev box use the Azure Functions Core Tools: func azure functionapp logstream --name <YourAppName> --resource-group <YourRG>

References:

• Azure Functions Flex Consumption plan hosting
• Metrics missing or incorrect for Linux Consumption

Hope this helps!

---

If the resolution was helpful, kindly take a moment to click on and click on Yes for was this answer helpful. And, if you have any further query do let us know.

Answer 2

For a Linux Azure Function on the Flex Consumption plan, diagnostics are accessed through Diagnose and solve problems in the Function App blade. Several diagnostics experiences and tools are specifically available and supported for Flex Consumption apps:

1. Open the Function App in the Azure portal and select Diagnose and solve problems.
2. From there, use one of the supported workflows instead of relying on a single “Diagnostic Tool” entry point:
   • Function App Down or Reporting Errors (Preview) to automatically check startup, configuration, runtime, and execution health issues.
   • Flex Consumption Deployment to see deployment history, package status, and deployment-related recommendations for Flex Consumption apps.
   • Flex Consumption Quota to review regional subscription memory/core quotas and related usage.
3. If the generic diagnostics home page itself fails with “Sorry, an error occurred. Please refresh the page and try again,” use the following alternatives while the portal experience is unavailable:
   • Go directly to Monitoring → Application Insights → View Application Insights data, then use Investigate → Failures and Logs with the provided Kusto queries (traces, requests, exceptions) to identify runtime errors and startup issues.
   • Use the Function App Down or Reporting Errors workflow once it is accessible again; it runs a series of checks (hosting plan, runtime version, configuration, extensions, execution health, etc.) and surfaces a focused diagnostic report with recommended actions.
4. Because Flex Consumption has some tooling differences (for example, Kudu logs are not supported for Linux Consumption and Flex Consumption plans), rely on the Flex-specific tools and Application Insights queries rather than Kudu when troubleshooting.

If the diagnostics blade consistently fails across browsers/sessions, the next step is to raise a support request so the portal diagnostics issue can be investigated, and in the meantime use Application Insights and the Flex-specific tools that are available.

---

References:

• Azure Functions diagnostics overview
• Resolve "Function App Down or Reporting Errors" issues
• Migrate Consumption plan apps to the Flex Consumption plan (platform-linux)
• Azure Functions Flex Consumption plan hosting