Once you are done with IOS-XR upgrade, which is not one line process, you should clean your repository of unused packages from previous image version. Not that you must, but it makes less noise once you start search for actual package version to install.
But what you should not forget to do is to check if FPD are compatible with installed image, and in case they are not, to start process of upgrading.
First, to check the status with command:
show hw-module fpd
In case you need to upgrade some HW, you will get in output NEED UPGD
To do an upgrade you will need to execute either upgrade hw-module location all fpd all force or if you want to upgrade just particular card you can use upgrade hw-module location {location of FPD} fpd {name of FPD}
Once upgrade is done, check again:
show hw-module fpd
Probably you will find that some cards are in process of upgrading, some of them are in status CURR which is wanted, and some of them might require reload, RLOAD REQ.
To reload FPD, you need to switch to admin mode, and execute command:
hw-module location all reload
Final status of all HW must be CURR before you are on safe side. Missing to upgrade FPD which are incompatible could cause unexpected behavior and problems in networking operations.