When you have parameters in a template with default values, Cuffsert should use these values like the CFN console does.

I often get errors like this (followed by a stack trace, which makes it look scary):

Invalid input for parameter key FooBar. Cannot specify usePreviousValue as true for a parameter key not in the previous template

This feels more like a bug in CFN than in Cuffsert, but working around bugs in CFN is what we have Cuffsert for, right?

It's probably not as easy as parsing the template and sending default values, that would risk overwriting overridden values, and there doesn't seem to be any flag to tell CFN to use default values.

A brute force way to solve it would be to capture the error, parse out the parameter, look for a default value, and run the update again with the default value, until there is an error for a parameter that has no default value, or the update proceeds.

@bittrance do you have a suggestion for a better strategy to solve this?