I have tried to upgrade a drupal 7 site drupal 8 in both a local dev environment and a live production environment but cannot get the UI to connect from the drupal 8 site to the drupal 7 database.
I am now under the impression this is not possible when each site is installed at a different domain and/or server.
Is my only option to have both 7 and 8 installed under the same account/domain/server in order for the upgrade/credentials UI page to connect?
First I thought this was a local setup problem (docker on debian as a subsystem of Windows 10 with Docker for Windows as an in-between for full docker use in debian), but then I tried it on a live production server and connection is refused or invalid from one domain to another same is was localhost w/ different port for each install.
I'm just looking for some clarification if what I'm attempting is possible as there appears to be nothing in regards to documentation regarding it and the only issues I've found via search clearly shows the user working with Drupal 8 upgrade where both sites are installed under the same account (ex. public_html/d7/... and public_html/d8/...) Nothing regarding making this work across two domains or even two different servers
This is a request opened a few weeks back explaining more the situation in the local setup as I initially thought the problem may be there. https://stackoverflow.com/questions/55926361/drupal-7-upgrade-to-drupal-8-upgrade-ui-fails-to-connect-to-localhost-database-w
So I thought I would ask for some clarification here before assuming what I was thinking and that this is a bug (which I now don't think is the case...)
Any help (if what I am trying to accomplish is possible) and or clarification would be greatly appreciated and I thank all in advance for the time it took to read this as well!