The error CEHE-00008 oAutherror : Failed to Get oAuth Token when trying to load the CloudExtend Gmail app in Google Chrome denotes that the account settings of the user email address is still tied to the old Gmail app. This requires for the user to remove the old Gmail app settings using the below instructions:
1). Load Gmail.
2). On the top right portion of the Gmail page, locate the icon Google Apps (screenshot below).
3). Click on the My Account option.
4). In this new page locate the Sign-in & Security portion and under it, click on Connected apps & sites.
5). Under the Apps connected to your account section in the right side, click on the Manage Apps link.
6). In this page, click each Celigo CloudExtend entries in here and hit Remove.
7). Now go back to your Gmail page and refresh it.