Oracle Message ORA-12342 - open mounts exceeds limit set on the OPEN_MOUNTS parameter

ERRORopen mounts exceeds limit set on the OPEN_MOUNTS parameter
CAUSEThe number of currently open mounts exceeds the value you specified on the OPEN_MOUNTS parameter.
ACTIONIncrease the value of the OPEN_MOUNTS parameter so that it accommodates the maximum possible number of open mounts to secondary databases.