Function host is not running

This usually means that there is some bad configuration in your function app which is causing the host to fail to start up. Things like having an invalid host.json or an invalid proxies.json file are a possible cause.

To diagnose, it's best to look at the function host logs. If you open your function app in the Azure portal and turn on log streaming, you should be able to get more information about what's going on.

If you're not able to find anything, please let us know the name of your function app either publicly or privately and we can help take a look at the logs for you.

I was getting this after adding dependency injection support - I had an error in the startup class which stopped the host from starting.