Symptoms

When we run the K2 for SharePoint - AppDeployment on our SP farm, we are getting the "Unable to connect to the K2 Environment with the given URL." and we cannot proceed with the installation. App will not deploy to app catalog.
 

Diagnoses

Initial checks:

Can we access AutoDiscover URL from SP Server:
The URL should be: https:///K2 Server Host Header]/autodiscover/autodiscover. This should pass back a JSON file and this will contain all of the site bindings for K2, similar to that in the environment library. This will also be useful to check over to see sites being used. If we can not connect to this URL then correct configurations are not in place to allow sharepoint server to talk to K2 server. This would explain the error.

Ensure that SSL is set correctly and we have a valid Certificate installed:
If SSL is not configured correctly or we also have bad certs we will see the "...can not connect to the given URL" error. This K2 URL must use SSL and in following, enter a URL that uses HTTPS connection.

Ensure proper account is being used for running App Deployment:
Most should have a dedicated install account to use on the domain. If an account with proper permissions is not being used then we will most likely run into issues with installing. This has not been directly linked to this issue but could cause other errors and it is always advised to ensure the correct account is being used whenever possible.
 

Resolution

AutoDiscover URL could not be accessed from the SharePoint server. This WFE was load balanced and one of the servers had a bad SSL cert/configuration. This has been fixed and now the app can be successfully deployed into the SharePoint App Catalog.