Oracle Solution for Error ora-01259

Solution for Oracle Error ORA-01259

ORA-01259: unable to delete datafile string

What triggered the Error:

A DROP TABLESPACE INCLUDING CONTENTS AND DATAFILES operation was not able to delete a datafile in the tablespace.

What should we do to fix it:

Subsequent errors describe the operating system error that prevented the file deletion. Fix the problem, if possible, and manually purge the file.