No ADR base is set Oracle RAC 19c

When I try connect to adrci appears below error:

adrci

ADRCI: Release 19.0.0.0.0 - Production on Thu Apr 14 14:51:54 2022

Copyright (c) 1982, 2019, Oracle and/or its affiliates.  All rights reserved.

No ADR base is set
adrci> show homes
No ADR homes are set
adrci> exit

Solution: check to see if there is a file adrci_dir.mif in $ORACLE_HOME/log/diag if the directory does not exist do the following :

mkdir -p $ORACLE_HOME/log/diag
printf "%s" "/u01/app/oracle" > $ORACLE_HOME/log/diag/adrci_dir.mif

"/u01/app/oracle" will be your ADR base, which is actualy oracle_base. After that adrci will work:

adrci

ADRCI: Release 19.0.0.0.0 - Production on Thu Apr 14 15:01:21 2022

Copyright (c) 1982, 2019, Oracle and/or its affiliates.  All rights reserved.

ADR base = "/u01/app/oracle"
adrci> show homes
ADR Homes: 
diag/asmtool/user_oracle/host_578647856_107
diag/asmtool/user_oracle/host_578647856_80
diag/asmtool/user_grid/host_578647856_107
diag/rdbms/testdb2/TESTDB2
diag/rdbms/testdb/TESTDB