No job functions found. Try making your job classes and methods public. If you're using binding extensions (e.g. Azure Storage, ServiceBus, Timers, etc.) make sure you've called the registration method for the extension(s) in your startup code (e.g. builder.AddAzureStorage(), builder.AddServiceBus(), builder.AddTimers(), etc.).
Issue started coming when we upgrade the .netframework from 4.7 to .netcore 3.0
You should follow this doc Migrating from 1.x to later versions for the task(you can also create a v3 function, and compare with your current v1 function, to see where needs to be changed).
But upgrading from v1 to later version is difficult and not recommended. For the best migration results, you should create a new function app in a new version and port your existing version 1.x function code to the new app.
If you still have the issue, please provide a sample and I can test it for you.
