I have relied on oerr to quickly find the meaning of error messages (ORA-, TNS-, RMAN-) on UNIX and Linux for decades.
How annoying that Oracle on Windows doesn’t provide this functionality! Sure, I can use the error documentation, or SQLCL (oerr is built in), but it wastes time.
I downloaded Oracle Database 12c Release 1 (126.96.36.199.0) for Microsoft Windows (x64), and found oerr now exists, but the message files don’t!
There is an easy solution: OERR on Windows and Oracle 12.1
Oracle 12.2 has a working OERR executable, but it is poorly designed.