For each Oracle Database 10g Release 1 (10.2) and higher instance that you upgrade to Oracle Database 12c Release 1 (12.1), perform the following steps:
Upgrade the database to Oracle Database 12c Release 1 (12.1).
Depending on where your database admin directory is stored, move the database wallet either to $ORACLE_BASE/admin/olddbuniquename/wallet or $ORACLE_HOME/admin/olddbuniquename/wallet. Note that $ORACLE_HOME is for the new Oracle Database 12c Release 1 (12.1). You may have to create the wallet directory.
Copy the old $ORACLE_HOME/network/admin/ldap.ora file to the new $ORACLE_HOME/ldap/admin/ldap.ora file. Alternatively, you can use Oracle Net Configuration Assistant to create a new ldap.ora file.
Use Oracle Wallet Manager to re-enable automatic login for the database wallet.
Use Oracle Net Manager to set the new wallet location in the sqlnet.ora file to the directory specified in step 2.