I was getting HTTP 409 errors when editing an Azure Function app, I couldn't understand why. A Bing search led to this blog post from Chaminda Chandrasekara which helped me out. If the configuration
WEBSITE_RUN_FROM_PACKAGE is set to
1, the app service editor returns 409 errors when you try to edit files. I set it to
0, restarted my function app, and I could make changes again.
When I'm done, I'll set it back to
1 for the sake of performance.