keith - Thanks for posting your question in the forum!
Usually that message indicates that the AOS device rebooted due to a software exception that occurred. You will want to check the "show version" output to see if there is a core dump message. Also, you will want to check the FLASH to see if there is an exception report that has been created.
Usually, if you are running the latest maintenance or feature release, I would suggest contacting ADTRAN Tech Support to investigate the cause. You can contact Tech Support in the following ways:
- Open a webticket by clicking on this link: https://www.adtran.com/openacase
- Open a ticket by emailing firstname.lastname@example.org
- Open a ticket by phone by calling 1-888-423-8726
Let us know if you have any questions.
I went ahead and flagged "Assumed Answered" on this post to make it more visible and help other members of the community find solutions more easily. If you feel like there is a better answer, feel free to come back to this post and select it with the applicable buttons. If you have any additional information on this that others may benefit from, please come back to this post to provide an update. If you still need assistance, we would be more than happy to continue working with you on this - just let us know in a reply.