A corrupted download is the #1 cause. Re-download the APK from a trusted mirror (e.g., Mediafire GD22 Mega Mod Menu fixed by CBF). Compare the MD5 hash if provided.
Geometry Dash 2.2 updates frequently break traditional, standalone mod menus due to changes in the game's code structure. The most reliable fix is adopting the Geode loader, which enables in-game installation of updated Mega Hack or GD Mega Overlay versions, bypassing version mismatch issues. For more details, visit Geode SDK Website OpenHack - Geode geometry dash 22 mega mod menu fix
Once you apply the fix, keep it stable: