Error 40103 Invalid signature in request credentials on calls with no parameters

Hi there,
I am doing an integration project with Duo using javascript. to administer users. API calls that use parameters work fine, but for calls where there are no parameters, I get the error above. Something is not right with the authentication string.

In the documentation for the Admin API it states:

“If the request does not have any parameters one must still include a blank line in the string that is signed”

So does this mean that the string passed to HMAC should end with the new line character, or a URL encoded empty string?

Hello, yes, try encoding the empty string (i.e. always encode the params even when there are no params).