Error on API Authentication via PHP GuzzleHttp Client

[user9377357]

Everything was working perfectly yesterday but all of a sudden today when resuming the development on the API testing, I am hitting this error message after the allowing of permission and should be redirected to the redirect URL and have the authentication code.

"There was an unexpected internal error. Please try again."

[John__B]

Hello user9377357,

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.

It looks like we'll need some additional information in order to assist with troubleshooting. If you could please provide us with the V3 API key that you’re using, a full example authorization request, and any timestamps/general timeframes you may have for when you encountered this issue we'll be able to better assist in pinpointing the cause of this error. Please provide this information securely by reaching out to us via email at webservices@constantcontact.com, we look forward to assisting you!

Regards,