How to Downgrade Xiaomi HyperOS to Previous Version

A Xiaomi no signal after update problem or SIM not detected HyperOS error is usually caused by a network setting reset failure, a SIM read glitch, or a carrier profile mismatch after the software change. The fastest fixes are restarting the phone, reseating the SIM, checking APN and network mode, and resetting mobile network settings before testing the SIM in another device.

Steps

Restart the phone and toggle Airplane mode once.

A fresh radio restart often restores carrier detection after an update and clears temporary Xiaomi SIM error states.
Remove and reinsert the SIM card carefully.

Power off the phone first, clean the SIM lightly, and check the tray for misalignment or dust that can block contact.
Check network mode and carrier settings.

Open mobile network settings and switch between 5G/4G/3G auto modes. If signal returns on 4G, the update may have affected 5G registration.
Reset mobile network settings.

Reset Wi-Fi, mobile network, and Bluetooth settings from system settings. Saved Wi-Fi and Bluetooth pairings may be cleared, but carrier detection often returns.
Test with another SIM or test the SIM in another phone.

If one phone fails with multiple SIMs, the issue is likely device-side. If one SIM fails in multiple phones, the issue is likely carrier-side or SIM-side.

Common Issues and Fixes

Issue	Likely Cause	Fix	Considerations
No bars after update	Radio firmware glitch after HyperOS update	Restart the phone, toggle Airplane mode, then reset network settings	Often temporary if caused by the update process
SIM not detected HyperOS message	Tray contact issue or SIM read failure	Remove the SIM, inspect the tray, reseat the card, and test a second SIM	Physical alignment problems can mimic software faults
Signal appears, then drops repeatedly	Unstable preferred network mode	Switch from 5G auto to 4G preferred and check for better stability	Useful when 5G registration became unstable after the update
Emergency calls only	Carrier registration failed or APN/carrier settings changed	Reselect the network operator manually, then return to automatic selection	May also require checking APN values from the carrier
Both SIM slots fail	System bug or baseband issue	Install the latest patch, clear cache if available, and back up data before a factory reset	If baseband information is missing, professional service may be needed

Quick Tips

Physical SIM issues can still happen after an update: A SIM that worked before may fail if the tray shifted slightly during removal or cleaning.
Check both SIM slots on dual SIM models: If only one slot is detected after the update, moving the SIM can help confirm a slot-specific fault.
Use factory reset as a last resort: It is best avoided until mobile data, photos, and app data are safely backed up.
Missing baseband version is a serious sign: If device information shows no baseband version, the issue may be deeper than normal settings and may require service support.

🤔Note:

Dual SIM Xiaomi phones may show a no signal problem on only one slot after a HyperOS update. Testing the same SIM in the other slot can quickly tell you whether the issue is related to the tray, the slot, or the software.

Can a Xiaomi update break SIM detection?

Yes. A software update can affect radio settings, carrier registration, or network mode behavior, especially right after a major HyperOS version change.

Why does Xiaomi show SIM error even when the SIM works elsewhere?

The phone may have a tray contact issue, corrupted network settings, or a firmware-related modem problem even if the SIM itself is still active.

💡Protip:

Before a factory reset or service visit, a local backup can prevent data loss. A device management tool such as Dr.Fone can help export photos, videos, and other files first.

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