I installed XAMPP with php7.2 and Magento 2.3 with sample data. Then, I went to the web setup wizard to install some extensions, but I get "Bad Credentials" every time I try to enter my private and public access keys. I've used these keys before and they worked. I also tried creating a new key, but that didn't change the result.
I have been experiencing the same issue since Magento 2.3 came out. I am trying to upgrade my system to Magento 2.30 through the setup wizard, however, when I try to log in with the access keys from the Magento market place I get the following error.
Invalid response line returned from server: HTTP/2 200
same here, since 2.3 I am getting error