BlockReportLeaseManager#checkLease will reject FBRs from DNs for conditions such as "unknown datanode", "not in pending set", "lease has expired", wrong lease id, etc. Lease rejection does not throw an exception. It returns false which bubbles up to NameNodeRpcServer#blockReport and interpreted as noStaleStorages.
A re-registering node whose FBR is rejected from an invalid lease becomes active with no blocks. A replication storm ensues possibly causing DNs to temporarily go dead (HDFS-12645), leading to more FBR lease rejections on re-registration. The cluster will have many "missing blocks" until the DNs next FBR is sent and/or forced.