SSM Agent update failure in Windows causing Permanent SSM Disconnection

2026-04-06 16:46:44.2356 INFO initiating cleanup of files in update download folder
2026-04-06 16:46:44.2458 INFO Successfully downloaded manifest
Successfully downloaded updater version 3.3.4108.0
Updating amazon-ssm-agent from 3.3.3572.0 to 3.3.4108.0
Successfully downloaded https://s3.us-east-1.amazonaws.com/amazon-ssm-us-east-1/amazon-ssm-agent/3.3.3572.0/amazon-ssm-agent-windows-amd64.zip
Successfully downloaded https://s3.us-east-1.amazonaws.com/amazon-ssm-us-east-1/amazon-ssm-agent/3.3.4108.0/amazon-ssm-agent-windows-amd64.zip
Initiating amazon-ssm-agent update to 3.3.4108.0
failed to update amazon-ssm-agent to 3.3.4108.0, failed to start the agent, ErrorMessage=checking svc and agent worker running err, The specified service does not exist as an installed service.
Initiating rollback amazon-ssm-agent to 3.3.3572.0
failed to rollback amazon-ssm-agent to 3.3.3572.0, failed to start the agent, ErrorMessage=checking svc and agent worker running err, The specified service does not exist as an installed service.
Failed to update amazon-ssm-agent to 3.3.4108.0

Start with the reported Windows update and rollback log, especially the service check that reports that the specified service does not exist. Trace the Windows agent update path that starts the new or restored agent and reproduce the failure if possible. Done means an update and rollback no longer leave the SSM agent permanently disconnected.

Written by the indexing model from the issue text.