New Auth - Blank Screen when authorizing

0 Votes

Very much a newbie, I'm trying to create a custom connector for Power Automate, managed to get this working using the older method (although it wouldn't refresh the token) but have hit a roadblock with the new method. 


I have input as before and when attempting to authenticate and grant permissions the login box shows up completely blank, literally nothing loads. 


The URL used to request is below:


Capital and bold indicates replacement of original value.


I have tried replacing the full stops in the redirect with html but still nothing. 


Any clues would be really helpful

0 Votes

Hello user7446451,


Thank you for reaching out to Constant Contact API Developer Support. My team is here to assist outside software developers with questions about building into Constant Contact's API.


After reviewing the login URL you provided, we were able to determine that the reason the URL did not properly redirect to the login page is due to a period character (.) in your state parameter value. We have documented this behavior and passed it up to our development team to review and update our documentation. I apologize for any inconvenience this may cause. We do know that the following character types will work in the state parameter value:


  •  Alphanumeric
  • Comma
  • Underscore
  • Hyphen


Removing the period from the state parameter value should allow you to successfully reach the login page and grant access to your application.


Please let us know if you have any other questions!



John B.
API Support Specialist
Did I answer your question? If so, please mark my post as an "Accepted Solution" by clicking the Accept as Solution button in the bottom right hand corner of this post.
0 Votes

Thanks for the feedback. I don't have control on the output for the parameters unless I can manage this in the swagger config or with some C# wizardry on Power Automate but being a newb have no idea where to start. 


I've chucked this issue to the Power Automate support forum to see if they have any input, real shame as it worked a dream (minus the need to authenticate every morning) using the old method!


Much appreciated, 



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