We were also notified by UPS that they are migrating to OAuth 2.0 for all APIs. Here are some information they provided:
For UPS customers using 3rd party shipping platforms or plugins
UPS customers who use a 3rd party shipping platform or software plugin to ship or use other UPS APIs will need to notify their vendor about the OAuth migration.?As a UPS customer, you<u>?do not need?</u>to obtain new API credentials, nor should the 3rd party ask you to obtain new credentials for them.?The 3rd party is responsible for updating their integration to OAuth auth-code. In the new flow, the 3rd party application will provide a UPS.com login screen for UPS customers to sign in using their existing UPS.com ID and password which will authorize API transactions on their behalf.
UPS customers who wish to continue using 3rd party applications will need to ensure that any UPS shipper account that they wish to use is added to their UPS.com ID(s) that they intend to use when logging into the 3rd party application. This can be done from the UPS.com profile page.
Source link: https://developer.ups.com/oauth-developer-guide?loc=en_US Is this something you need to update on your end as well?