[Azure Functions][V4] Azure Functions 4.0.0-preview.5.16714 (breaking changes)

[anthonychu]

The next preview release of the Azure Functions v4 host is starting today and the rollout is expected to complete in a few days. In preparation for the GA of Azure Functions v4 in November, this preview release contains several planned breaking changes. Please review the breaking changes and take action to update your v4 apps.

See the documentation about breaking changes in v4.

Application Insights breaking change

One change with significant impact is applications that have APPINSIGHTS_INSTRUMENTATIONKEY or APPLICATIONINSIGHTS_CONNECTION_STRING app settings configured, but do not have the Application Insights extension installed will no longer start.

To avoid downtime caused by this breaking change:

• If you have a v4 .NET in-process or isolated app, install the packages described in this announcement and redeploy your app.

• If you have a v4 app on another language, there will be an upcoming Azure Functions extensions bundle release that will include the Application Insights extension. We will update this issue when it is available. Until then, remove both APPINSIGHTS_INSTRUMENTATIONKEY and APPLICATIONINSIGHTS_CONNECTION_STRING app settings from your function app. This will prevent the host from failing to start because Application Insights is configured but the extension is missing.

Discussions

Please post any questions in the discussion issue - https://github.com/Azure/app-service-announcements-discussions/issues/249