In earlier OS, I never had problems in copying files t external hard drives using copy option or drag and drop. But on upgrading to el capitan, this is not possible. Please help with a solution.
MacBook Pro, OS X El Capitan (10.11.3)
What happens when you try?
What is format of the external drive?
A Mac can't natively write to a NTFS formatted drive but there are apps like
External HDs come formatted NTFS and some may come with an app that apps writing to NTFS formatted drives. You have to update the app to be compatible with El Capitan. Try the HDs manufacturer's support site for an update
I cannot copy files / folder to external hard drive in el capitan
