Hi! specifically about the HPE OfficeConnect 1920S Switch series starts here; select "1920S" as Switch series and then pick up a software release (actually that portal provide a direct link to PD.02.09 but it's not updated, see below).
Another way is to go directly to HPE MyNetworking Portal (that is my preferred way since I always know the Switch product name or its SKU) and, once there, filter by searching the right SKU for your Switch (it is the JL381A)...for the entire HPE OfficeConnect 1920S Switch series...the real latest firmware is the PD.02.10 software version (and not the PD.02.09 as reported on the other side cited above <- links are not updated as often as they should).
The upgrade from PD.01 software branch (old) to PD.02 software branch (new/current) should be performed normally following Release Notes best practices (IIRC there are no specific restrictions or requirements).