Hi Osman...
AFAIK - There should not be any issues if you execute the post installation steps properly (PI upgrade wizard)
There used to be an issue in updating the cache post upgrade as it uses PIDIRUSER instead of PICACHEUSER (till 7.3 and 7.31upgrade i'm sure it was there).
May be the below upgrade guide helps 
https://websmp201.sap-ag.de/~sapidb/011000358700000422052013E/uug_nw740_sr1_abapjava.pdf