A situation was found in which the partition file index contained no keys after deleting the indexes and rebuilding. This occurred for a "covering index" that included the partition key, and was not ordered as the partition key. In this specific case, the rebuild terminated before rebuilding the indexes, and returned no error. The logic assumed the indexes were open, but at this point of the rebuild they were all closed, causing FACS_ERR (26, file number not in use) which was not propagated. Rebuild logic was altered to set up ISAM-level relationships between the covering index and the partition key to correct this.