Your app is currently in read-only mode because you have published a generated function.json
If you published your Azure function from Visual Studio and are seeing the message:
Then follow below steps:
Click on = Platform Features =>
Click on App Service Editor =>
Expand Your Function Name =>
Click on function.json =>
Delete the line "generatedBy":
"generatedBy": "Microsoft.NET.Sdk.Functions-1.0.24"