Incompatible namespaceIDs issue

Does anyone know about Incompatible namespaceIDs issue in Hadoop?

In Hadoop, the name node generates new namespaceID every time we format HDFS. This is to differentiate among current version and previous version. This is good as we can always rollback to previous version if there is something that should be modified, which may not be possible if namespaceID is not unique for every formatted instance.