Reason: the wallet key may be changed.
Solution: confirm issue and replace the faulty key using backup key.
How to confirm the wrong wallet?
1. Search the right wallet:
$ORACLE_HOME/bin/mkstore -wrl {WalletInstance} -viewEntry ORACLE.SECURITY.DB.ENCRYPTION.MASTERKEY
2. Check the wallet value from database?
select utl_raw.cast_to_varchar2( utl_encode.base64_encode('01'||substr(mkeyid,1,4))) || utl_raw.cast_to_varchar2( utl_encode.base64_encode(substr(mkeyid,5,length(mkeyid)))) masterkeyid_base64 FROM (select RAWTOHEX(mkid) mkeyid from x$kcbdbk);
3. Compared above wallet values, if they are different, then the wallet value has been modified.