iPhone Error Code 21: How to Fix It

Medium 30-60 minutes High Severity Verified June 2026
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Error Code
Error 21
Brand
iPhone
Product Type
mobile
Severity
High
DIY Difficulty
Medium
Estimated Fix Time
30-60 minutes
iPhone Error 21 appears when iTunes fails to restore your iPhone, typically due to jailbreak detection or hardware communication issues. This error prevents your device from completing the restore process and can leave your iPhone stuck in recovery mode.
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Tools You'll Need

How to Fix Error Code Error 21

  1. Update iTunes and Computer Software

  2. Check USB Connection

  3. Disable Security Software Temporarily

    Only disable security software temporarily and re-enable immediately after troubleshooting.

  4. Try Different Computer

  5. Enter DFU Mode

    DFU mode will erase all data on your iPhone. Ensure you have a backup before proceeding.

  6. Use Recovery Mode

  7. Check for Hardware Issues

Parts You May Need

Original Apple Lightning Cable
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Original Apple Lightning Cable
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Original Apple Lightning Cable
Check Price on Amazon
Original Apple Lightning Cable
Check Price on Amazon
Original Apple Lightning Cable
Check Price on Amazon
Original Apple Lightning Cable
Check Price on Amazon
Original Apple Lightning Cable
Check Price on Amazon
Original Apple Lightning Cable
Check Price on Amazon
Original Apple Lightning Cable
Check Price on Amazon
Original Apple Lightning Cable
Check Price on Amazon
Original Apple Lightning Cable
Check Price on Amazon
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When to Call a Professional

Contact Apple Support or visit an authorized repair center if the error persists after trying all software solutions, especially if you suspect hardware damage or if your iPhone is still under warranty. Professional diagnosis is recommended for potential logic board or charging port issues.

Frequently Asked Questions

What causes iPhone Error 21?
iPhone Error 21 is typically caused by jailbreak detection during restore, hardware communication issues between iPhone and computer, corrupted firmware, or problems with the USB connection or cable.
Will fixing Error 21 erase my iPhone data?
Yes, most solutions for Error 21 involve restoring your iPhone, which will erase all data. Always backup your iPhone before attempting these fixes if possible.
Can I fix iPhone Error 21 without iTunes?
While iTunes is the primary tool for fixing Error 21, you can try using third-party tools like 3uTools or ReiBoot, though iTunes remains the most reliable method recommended by Apple.
Is iPhone Error 21 a hardware problem?
Error 21 can be either software or hardware related. Try software solutions first, but if they fail, it may indicate hardware issues with the charging port, logic board, or other internal components.
How do I prevent iPhone Error 21 in the future?
Avoid jailbreaking your iPhone, use only original Apple cables, keep iTunes updated, and handle your iPhone carefully to prevent hardware damage that could cause communication errors.

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