If the phone is lagging or the storage error won't disappear after deleting files, a soft reset clears the RAM and temporary system state without deleting your data. Press and hold the Volume Down
If you can still boot into the OS:
If your Lumia 650 is reporting that its own internal storage is full due to "system" or "other" files, follow these steps to clear space: Clear Temporary Files: This Device Temporary files Select the categories you want to remove and tap Remove files Move Apps to SD Card: lumia 650 emergency files full
Before using emergency files, keep in mind: If the phone is lagging or the storage
Safe immediate fixes (non-destructive, prioritized) lumia 650 emergency files full