Unable to integrate Jira and Zendesk, specifically when authenticating at the Account Verification step. This is step #6 as described in the official guide for integrating JIRA and Zendesk here.
The Zendesk subdomain is pre-filled, un-editable, and isn't populated with the preferred target Zendesk instance.
The JIRA instance you're trying to integrate is a copy of another JIRA instance that has already been integrated to another (separate) Zendesk instance.
Un-installing and re-installing the add-on did not fix the problem
- In the home directory of the JIRA instance that you're attempting to integrate, rename the file
- Uninstall then re-install the JIRA add-on (the guide can be found here)