In the vSphere Client restore dialog for Native Key Provider, selecting the .p12 backup file results in a parsing error : The selected file cannot be parsed
vCenter server 8.x
The .p12 file was created without a password (empty) or with a forgotten/incorrect one, causing vCenter's parser to reject it as invalid during import validation
Recreate the .p12 backup from the original NKP using the vSphere Client (Actions > Backup), explicitly setting a memorable password or none if previously empty, then retry restore with matching password.