Hadi Fadlallah discusses what was the bane of my existence for about 3 months in 2010:
In this article, we will briefly explain the VS_NEEDSNEWMETADATA SSIS exception, one of the most popular exceptions that an ETL developer may face while using SSIS. Then, we will run an experiment that reproduces this error. Then, we will show how we can fix it.
This was really annoying prior to SQL Server 2008 (at least, that’s my early-morning recollection of when the SSIS engine started trying to auto-fix this) and has been mildly annoying since. I had far too many conversations which I could summarize as “Yes, I understand that this Excel spreadsheet is basically the same, but it’s different in that the casing on one header column has changed slightly and that breaks the entire system.