Oracle 8.1.7 -- RMAN-06172: not connected to recovery catalog database

Problem

You get error RMAN-06172: not connected to recovery catalog database when you are trying to issue any command at rman prompt

bash-2.03$ rman target /

Recovery Manager: Release 8.1.7.4.0 - Production

RMAN-06005: connected to target database: xxxxxx (DBID=00000000)

RMAN> list backup of database;

RMAN-03022: compiling command: list
RMAN-03026: error recovery releasing channel resources
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03002: failure during compilation of command
RMAN-03013: command type: list
RMAN-06172: not connected to recovery catalog database

Solution

Connect to rman with NOCATALOG option.

bash-2.03$ rman target / nocatalog

Recovery Manager: Release 8.1.7.4.0 - Production

RMAN-06005: connected to target database: xxxxxx (DBID=00000000)
RMAN-06009: using target database controlfile instead of recovery catalog

RMAN>