KB2029: SQL Transaction Log Backup - Failed to prepare ...
https://www.veeam.com/kb202927.04.2015 · Veeam Backup & Replication is designed to only allow one Backup Job to be responsible for a SQL servers log backup. This is done to prevent possible restore issues. In order to prevent another job from attempting to take over the SQL log backup process there is a 7 day timeout in which the job currently responsible for the SQL log backup must not run.