App error 523 ni sababu ya third party softwares...i.e applications umeinstall on your device,to solve hio issue,use your DM yako ku uninstall every application kwa device yako/swipe(clean kila kitu kwa simu)..back up important stuff kwanza......Then upgrade version ya OS yako,all these through your DM.Pliz retort if it worksregards