Common advice from modding forums includes:
Before installing a mod from iHappyMod, any existing version of the app (official or previous mod) must be completely uninstalled to clear the package name and signature cache. ihappymodcom fix
: Try switching from Wi-Fi to mobile data (or vice-versa). Many users find that mobile data is more stable for these downloads. Background Auto-Start ihappymodcom fix
“Downloaded the iHappyMod fix from a YouTube link — now my phone has pop-up ads every 30 seconds. Had to factory reset.” ihappymodcom fix