While installing System Centre Data Protection Manager 2019 (DPM 2019) and setting your product key, you might get an error message:
The DPM product key is invalid. (ID: 858) Enter a valid DPM product key. The product key is locate don the back cover of the data protection manager product DVD
We’ve found that if you have copied the key from MVLS or similar and then pasted directly into the setup, it fails with the above error. If you simply type the same key instead, it works fine!