Differentials should be running, but full backups are always run. This message is in the job log.
2012-05-12 18:16:18.913]: WARNING - The current task depends on the following files, which are corrupted or missing from the repository:Abc123_420d42f3-7f15-b492-0200-64b9550dc95c/ABC123_20120511_194331_1372b41b-2708-44bd-a45d-55b6eba252ab/ABC123_20120511_194331_F.Manifest.metadata; Abc123_420d42f3-7f15-b492-0200-64b9550dc95c/Abc123_20120511_194331_1372b41b-2708-44bd-a45d-55b6eba252ab/ABC123_20120511_194331_F.VmConfig.metadata
Root cause being investigated - Password change on repo share started this instance.
Files are not really corrupted, but could have been "missing" if the job could not find them.
Edit the job, re-connecting it to the existing repository, and differentials will pick up where they left off.
AG. Notes from a different case. Ranger 5.3.1. repo points to the local E: drive. Admin share is in use. We created an explicit share with Full Control for Everyone. Changed ShareName column in RepositoryCIFS table, restarted Ranger Service. Incremental (in our case) works.
We do not recommend to use admin shares.
Case ref 1033960 - still being evaluated.