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Last week, some readers reported error 21 on the iPhone 3GS.
How do I fix Error 21 on my iPhone?
Restart iTunes by updating iTunes.Update to fix iTunes error IPhone 21, 4g.Disable or customize yourantivirus.Checking the hosts file.Disconnect unnecessary USB devices.Checking the sensor cable.Duuse DFU mode to fix iTunes error 21.
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How do I fix Error 21 on iPad?
Switch to the “OFF” position and hold the power button for 3 seconds. After entering DFU mode, the real iPad screen goes blank, and the iTunes software applications display the message “The device is in recovery mode.” Finally, your iPad device will start restoring iOS firmware.
Mac Studio and Studio Display can be purchased here!
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