SQL Server Backup and Restore
Backup sets tripped me up.
I needed to create a new backup with some additional data to test the patch I was working on. I was using a script from out CI pipeline to replicate that process as closely as possible when restoring databases locally. Being unfamiliar with backup sets, when creating my backup with the new data, I hadn't included INIT in the T-SQL command. As the RESTORE command included WITH FILE = 1 I kept restoring the old version of the database. RESTORE HEADERONLY was what I needed to identify the multiple backups in the set.