Clean Flash vs Dirty Flash
When updating your custom ROM, you have two options: clean flash or dirty flash. Here's when to use each.
What's the Difference?
Clean Flash (Full Wipe)
Wipes: System, Data, Cache, Dalvik
Start fresh → Flash ROM → Setup from scratch
When to use:
- Major version upgrades (Android 13 → 14)
- Switching between ROMs
- Experiencing bugs or issues
- First time installing a ROM
- Recommended by ROM developer
Dirty Flash (No Data Wipe)
Wipes: System, Cache, Dalvik only (keeps data)
Keep apps/data → Flash ROM → Continue using
When to use:
- Same ROM updates (weekly builds)
- Minor version updates
- ROM developer confirms it's safe
- Same Android version
When It's SAFE to Dirty Flash
✅ Updating from ROM build to newer build of SAME ROM ✅ ROM's changelog says "dirty flash OK" ✅ No base changes (vendor, firmware) ✅ Same Android version
Example: Evolution X 9.0 → Evolution X 9.1 (same Android 14)
When You MUST Clean Flash
❌ Switching ROMs (LineageOS → PixelExperience) ❌ Major Android version jump (13 → 14) ❌ Changelog mentions "clean flash required" ❌ Base/vendor changes required ❌ Persistent bugs after dirty flash
Examples:
- Evolution X → crDroid
- Pixel Experience A13 → A14
- Any ROM saying "clean flash recommended"
How to Clean Flash
In TWRP:
1. Backup first! (Backup → Boot, System, Data)
2. Wipe → Advanced Wipe
3. Select:
- Dalvik/ART Cache ✓
- System ✓
- Data ✓
- Cache ✓
4. Swipe to wipe
5. Install → Select ROM
6. Install → Select GApps
7. Reboot System
With Format Data:
For persistent issues, use Format Data:
Wipe → Format Data → Type "yes"
⚠️ This erases EVERYTHING including internal storage!
How to Dirty Flash
In TWRP:
1. Backup first! (Safety net)
2. Install → Select new ROM build
3. Swipe to flash
4. Wipe → Advanced Wipe → Dalvik/Cache only
5. Reboot System
Via ADB Sideload:
adb reboot recovery
# In TWRP: Advanced → ADB Sideload
adb sideload rom-update.zip
Dirty Flash Risks
Potential Issues:
- Apps crashing
- System instability
- Random reboots
- Features not working
- Boot loops
If Problems Occur:
- Boot back to TWRP
- Clean flash the same ROM
- Restore apps from backup
ROM-Specific Guidelines
LineageOS
- Same version: Dirty flash OK
- Different version: Clean flash recommended
Evolution X
- Weekly builds: Usually dirty flash OK
- Major updates: Check changelog
Pixel Experience
- Generally prefers clean flash
- Check their Telegram for update notes
crDroid
- Minor builds: Dirty flash usually OK
- Check changelog always
Quick Decision Chart
Update Type
│
┌───────────────────┼───────────────────┐
│ │ │
Same ROM Different ROM Major Android
Same Android Version
│ │ │
Dirty OK Clean Flash Clean Flash
(usually) Required Required
Best Practices
Always Before Updating:
- Read the changelog - Developers will specify
- Create NANDroid backup - Safety first
- Check Telegram/XDA - Community feedback
- Have previous ROM zip - Rollback option
Recommended Workflow:
1. Download new ROM
2. Create backup
3. Read changelog notes
4. If "clean flash": Wipe data, flash, setup fresh
5. If "dirty flash OK": Flash over existing, wipe dalvik
6. Boot and verify
7. If issues: Restore backup or clean flash
Dirty Flash Troubleshooting
Bootloop After Dirty Flash
1. Boot to TWRP
2. Wipe → Advanced → Dalvik, Cache
3. Try booting again
4. If still loops: Clean flash required
Apps Force Closing
Settings → Apps → [App] → Clear Data
Or flash ROM again with clean wipe.
System UI Issues
Try wiping just cache:
Wipe → Advanced → Cache, Dalvik
If persists: Clean flash.
Summary Table
| Situation | Method | Wipe |
|---|---|---|
| Same ROM minor update | Dirty | Dalvik, Cache |
| Major update (same ROM) | Check changelog | Varies |
| Different ROM | Clean | System, Data, Cache |
| Android version jump | Clean | Format Data |
| Constant bugs | Clean | Format Data |
When in doubt, clean flash! A fresh start takes longer but avoids headaches.
Keywords: dirty flash vs clean flash, dirty flash Android, update custom ROM safely, clean install ROM