You can get around this by setting your route to the following:

@app.route(route="")

Without a doubt, the Azure Functions is the worst service I have ever seen across all Azure, GCP and AWS. Microsoft should be ashamed of launching such a poorly documented and flakey service.

I've spent countless hours fighting vague error after vague error.

Dropping support of V1 Python apps (InternalServerError) (this previously worked fine)

Lack of support for in terraform for V2 models (not really Microsofts fault tbh)

Having to have a very specific configuration to even allow function apps to be invoked by logic apps.

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Not allowing custom routes with logic app invocation

Then there are issues with logic app providers themselves, such as the RSS component, which double encodes URLs, so I have to go into code view, manually remove an encoding, and re-save!

Although the above workaround will do the job for now, I have no doubt that Microsoft will make more changes and break things again. Honestly, this service is terrible compared to AWS Lambda.