@Reddy3  There is not enough history or detail to understand what lead to the corruption of your NiFi HD DBs. However, the NiFi H2 DBs are used to hold flow configuration history (what user did what on the canvas) and authenticated user server side tokens. These DBs can be removed/renamed and on startup NiFi will created new DBs.  Removing these will have no impact on your flow.xml, content, etc... You will simply lose your flow configuration history (will start over from this point forward tracking changes) and your users will be forced to login again. Hope this helps, Matt ... View more