Existing user (has been using 365 without issues for months) receiving the following error when attempting to approve a PO. This has been working fine. No changes to workflow, rights, or any other setup. Thoughts?

Existing user (has been using 365 without issues for months) receiving the following error when attempting to approve a PO. This has been working fine. No changes to workflow, rights, or any other setup. Thoughts?
Hello,
Can you give me the following information (feel free to send to me in a Private message)
- Tenant Name
- Time and Time Zone of reproducing the error on screen
Thanks,
Chris