How to resolve "Unauthorized Endpoint" or "The session has expired. Please refresh the page" error.

Summary

After applying the API access token on the Salesforce package an "Unauthorized Endpoint" message appears and the page is stuck in a loop:

Another error that can be seen after adding the API token:

Environment

Jira Cloud or Jira Server

Cause

Environment	Cause
Cloud	This is usually caused by the Connector's server URL not being configured in 'Remote Site Settings'.
Server	This is usually caused by the Jira instance URL not being configured in 'Remote Site Settings'.

Resolution

Environment

Resolution

Cloud

Go to the Salesforce page. In the Quick Find box in the sidebar, type "remote site settings".
Click the Remote Site Settings link that appears.
On the All Remote Sites screen, click the New Remote Site button.
On the Edit Remote Sites screen, enter the following details:
Remote Site Name: Jira
Remote Site URL: https://sfjc.integration.appfire.app
Click Save.
Please revoke the access from both ends
Re-authorize the connection
Copy a new API Token from the Connector configuration in JIRA

Server

Go to the Salesforce page. In the Quick Find box in the sidebar, type "remote site settings".
Click the Remote Site Settings link that appears.
On the All Remote Sites screen, click the New Remote Site button.
On the Edit Remote Sites screen, enter the following details:
Remote Site Name: Jira
Remote Site URL: <enter your Jira instance URL>
Click Save
Please revoke the access from both ends
Re-authorize the connection
Copy a new API Token from the Connector configuration in JIRA

If after following all these steps the issue persists, please verify that your Jira instance meets all the system requirements, you can find more information about it here.