ORA-19914: unable to encrypt backup
Cause: RMAN could not create an encrypted backup. This message will be accompanied by other messages that give more details about why the encrypted backup could not be created. The most common reason for this message is that you are trying to create a backup that can be transparently decrypted, and the database external security device is not open
Action: If the external security device is not open, then open it. If the external security device is not configured, then the only type of encrypted backup that you can create is a password-based backup
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