Issue
When attempting to respond to a task with the Nintex Outlook Addin, users enter their account information and encounter "An Error Has Occurred."
Resolution
Fist confirm that the task list being used follows the '/Lists/TaskListName/' URL format. If the Task list has a custom URL such as '/SiteName/TaskListName/' the addin can error. If the URL doesn't follow the expect path format, create a new task list for the workflow and ensure that the URL has the following format:
https://SiteURL/sites/SiteName/Lists/TaskListName/