After update OS X EI Capitan, external hard disk format changed I always use the same external hard disk on my Mac formatted as OS X Extended (Journaled). After upgrading my OS, it's recognized as NTFS volume now.

What should I do?
If what you say is true (and I must say, it sounds extremely unlikely), then your only options really are:


EITHER Copy all the data from the external drives, and then reformat them as HFS+ (journaled) and copy the data back.
OR Leave them as they are.


There really is not much else you can do with them.