can we restore the F5 firmware older version from UCS file ?

kumar0303 The UCS file does not control what code version the F5 is running. If you upgraded from 16.1.3.3 to 16.1.4.2 into different partitions then the old partition should still be in place and you can boot back into the old code version partition and the configuration will still be in place.

Exactly Like Paulius said , you should reboot and return back to the old boot location.

I just want to add , if you performa downgrade from 16.1.4.2 to v16.1.3.3 , you will loose your configuration and you will have to resore back the UCS " v 16.1.3.3". 

So use Paulius recommendation. 

Also remember when you downgrade your OS from higher version 16.1.4.2 to lower version v16.1.3.3, the new changes you have done in the configuration of higher version 16.1.4.2 , will not be replicated when you install the configuraiton file or installation from higher version to lower version is not allwed.

All the new changes done in the higher version 16.1.4.2, after booting to the older version v16.1.3.3, you have to repeat all those new changes to get the latest configuration.

Also you must have a separate partion to boot.

Once a partiton has been re-write you cannot downgrade the same partiton as its a workign partiton, and it cannot be deleted or erased, whitout booting to a new or temporary partition.

Hi kumar0303 , 

To change your bootlocation and reboot directly from Cli 
you can use this command : 

tmsh reboot volume <location>

For Example: 

tmsh reboot volume HD1.1

More info here in this Article : https://my.f5.com/manage/s/article/K93414734