Created a snapmirror relationship within Cloud Manager, moving data from onprem to cloud, broke the mirror, changed data on volume, and attempted reverse resync in Cloud Manager.
Got message below in Cloud Manager.
errorMessage: Error while establishing replication between ntap14 (SVM svm_ntap14, Volume testvol) and ntap12 (SVM test, Volume testvol): SnapMirror last transfer error: No common Snapshot copy found between svm_ntap14:testvol and test:testvol.. Verify network connectivity between the source and destination systems and then try again.
Second error below is from event log.
smc.snapmir.update.fail: Snapmirror update from source volume 'test:testvol' to destination volume 'svm_ntap14:testvol' failed with error 'Destination svm_ntap14:testvol must be a data-protection volume.'. Relationship UUID 'd89df68a-bb20-11e7-9dc0-000d3a1cba66'.
mirror relationship did show up in the original source Netapp in System Manager, but my only options are resync and reverse resync.