If you're experiencing this issue, try the below troubleshooting options:
Try again from a different browser and an incognito tab.
Reinstall your browser and ensure to use the most up-to-date version.
If the issue persists, raise a new case online and reference the title of this article providing the following:
Confirmation you performed the above troubleshooting.
Permission to access your system.
Screenshots or screen records of the planner with the error message.
Names of users affected.