Description: Failed to decrypt protected XML node "DTSassword" with error 0x8009000B "Key not valid for use in specified state.". You may not be authorized to access this information. This error occurs when there is a cryptographic error. Verify that the correct key is available.
Basically it happens because data has been encrypted with a user key that is different from the key of the SQL Server Agent Impersonated Service.
Select File > Save Copy of
The bottom box is greyed out called protection level.
Click on the weird box with a dot in the middle on the right and a dialog will pop-up.
Change the package protection level to the last option "Rely on server storage and roles for access control" .