Resolve common runtime issues after deployment

This article describes the common causes of runtime issues and provides solutions to resolve these issues.

If your application is experiencing issues after deployment, it's important to determine whether the problem is related to deployment or runtime. A deployment issue can cause the wrong set of files to get deployed to your function app, or it can cause some files not to get deployed at all. A runtime issue occurs after deployment. The files in your wwwroot directory are exactly as they should be, but the function app isn't running correctly. When this scenario occurs, the technique that you used to deploy your site is no longer relevant. For a runtime issue, you should, instead, focus on what your code is doing at runtime and how it's failing.

Common causes for application runtime issues after content deployment

Runtime failure can occur for any of the following reasons:

• The function runtime can't start because the function app has lost access to the storage account.
• In the runtime sandbox environment of Azure Functions, something is blocking certain operations that work on your local computer.
• Your Azure Functions app isn't configured correctly. For example, the function host doesn't start up because of incorrect values in the following settings:
  • Runtime or language version
  • Triggers connection strings
  • Key vault settings
• An external dependency (such as a database or messaging system) isn't set up correctly and is causing time-out errors.
• Sync triggers failed. This causes an incorrect loading of functions.
• Your code makes invalid assumptions about paths, such as hard-coding a path that exists only on your local computer.

Solutions

To fix runtime issues after the content deployment, try one or more of the following methods:

• Manually restart the function app.
• Run the Azure Functions Diagnostics to quickly diagnose and solve common function app problems.
• Verify whether storage connections are set up correctly and that the storage account is accessible.
• If you've enabled Application Insights for your function, see Application Insights logs to learn more about the full exception trace or error message that's causing errors.
• Review the function runtime migration guides if your deployment is updating the function app runtime or language version.

Contact us for help

If you have questions or need help, create a support request, or ask Azure community support. You can also submit product feedback to Azure feedback community.