Xiaomi’s Inadmissible Signature: What is the Mistake and How to Fix It

If your smartphone, TV or other Xiaomi device suddenly issues an “Invalid Signature” message (or Invalid Signature in English), it means that the system has detected a problem with the digital signature of the firmware, application or update file, such an error blocks the installation of the software, since the device cannot confirm its authenticity and security, most often when you try to update the firmware through Recovery, install custom software or even with a regular OTA- update.

In this article, we will discuss all possible causes of the error, from corrupted files to version incompatibility, and give step-by-step instructions for its elimination for different Xiaomi devices (smartphones, TVs, routers). Particular attention will be paid to the risks when using informal firmware and how to avoid “bricking” the gadget. If you are not sure about your actions, you should contact the service center, but most problems are solved at home.

What does the “Unacceptable Signature” error mean on Xiaomi?

A digital signature is a kind of manufacturer's "seal" that confirms that a firmware or application file has not been altered by malicious actors. When a Xiaomi device sees an "Ineligible Signature" message, it signals that:

• 🔹 The firmware file is corrupted (e.g., not fully downloaded or modified by a virus).
• 🔹 The signature of the file does not match the expected (e.g. firmware from another region or model).
• 🔹 The device attempts to install unofficial software without unlocking the bootloader.
• 🔹 Security settings have been lost (e.g. after a reset or root rights).

On Xiaomi smartphones (Redmi series, POCO, Mi), the error most often appears when updating via Recovery or Fastboot, and on Mi TV TVs - when trying to install firmware from a flash drive. In rare cases, it can occur with a normal OTA- update, if Xiaomi servers are temporarily unavailable or the file was downloaded with an error.

⚠️ Warning: If the error occurred after trying to install custom firmware (for example, LineageOS or Pixel Experience), this means that the device bootloader is not unlocked or the firmware signature does not match the expected. Continuing the installation may lead to a complete loss of functionality of the gadget!

The main reasons for the error "Invalid signature"

To effectively fix the problem, you need to understand the source of the problem, and here are the most common reasons for the signature error on Xiaomi devices:

For example, if you downloaded firmware for Xiaomi Mi 11, but you try to install it on Redmi Note 10 Pro, the system will give a signature error, since the files are for different devices, the same will happen if you try to install global firmware on a device with the Chinese version (and vice versa) without first unlocking.

How to check the firmware file for integrity?

Before you try to fix the bug, make sure the firmware file is not corrupted. Here are 3 ways to check:

1. Hash Comparison (MD5/SHA-1) – Xiaomi’s official websites list their hash sums next to the firmware, download the verification utility (e.g. MD5 & SHA Checksum Utility for Windows) and compare the hash to the original one. If they don’t match, the file is corrupted.
2. File size check: Check the size of the downloaded file against the size of the site, and even a slight discrepancy (e.g., 2.3 GB instead of 2.35 GB) can indicate damage.
3. Try to unpack the archive. If the firmware is.zip or.tgz, try unpacking it. If the archiver comes up with an error, the file is dead.

For Xiaomi devices, official firmware can be downloaded from the sites:

• 🌍 Official website MIUI (global versions)
• 🇨🇳 Chinese Portal MIUI (required VPN)
• 🔧 Xiaomi Firmware Updater (unofficial but reliable source)

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If you download firmware through torrent or third-party sites, always check user reviews about the file. Often, modified or infected versions are distributed under the guise of official firmware.

Step-by-step: how to fix the error "Impermissible signature"

Depending on the cause of the error, the ways to fix it will be different, and here's a universal algorithm that will help in 90% of cases.

1.Reset the device and try again

Sometimes the error is caused by a temporary system failure.

• 🔄 Turn off the device and turn it on again.
• 📶 If an error occurs when OTA- updates, connect to another Wi-Fi network or use mobile internet.
• ⏳ Wait 10-15 minutes and repeat the installation.

2. Download the firmware again.

If the file is corrupted, it must be downloaded:

Make sure you choose firmware for your model and region, for example, the Redmi Note 12 Pro+ 5G global version needs firmware labeled Global, not China.

3. Check the date and time settings

Incorrect date/time may lead to a signature error, as the system checks the validity of certificates to correct:

1. Go to Settings → System → Date and time.
2. Activate the Automatic Date and Time option.
3. If the option is already on, turn it off, set the correct date/time manually, then turn on the automatic mode again.

4.Update via Fastboot (for smartphones)

If the error occurs in Recovery, try installing the firmware via Fastboot:

1. Download the Fastboot firmware for your model.
2. Unpack the archive in a folder on your PC.
3. Connect your phone to your computer in Fastboot mode (clip Volume Down + Power when the device is off).
4. Launch the file. flash_all.bat (for Windows or flash_all.sh (for macOS/Linux).

⚠️ Warning: Installation via Fastboot completely erases data from the device!

5. Unlock the bootloader (for custom firmware)

If you are trying to install unofficial software (like LineageOS or HavocOS), you should first unlock the bootloader:

1. Apply for unlocking through the official Xiaomi website.
2. Connect your device to your PC in Fastboot mode and start the Mi Unlock Tool.
3. Wait for the unblock confirmation (it can take up to 72 hours).

After unlocking, repeat the installation of the firmware.

Features of the Mi TV Error

On Xiaomi TVs (Mi TV 4/5, Mi TV A, Mi TV Q series), the "Unacceptable Signature" error usually appears when you try to update the firmware with the USB- drive. Here's what to do:

1. Format the flash drive in FAT32. Xiaomi TVs do not support the NTFS or exFAT file system for updates. Use a flash drive up to 32 GB formatted in FAT32.
2. Name the firmware file correctly. The file must be called update.zip and be located at the root of the flash drive (not in the folder!). Some models require the name miui_TV_update.zip.
3. Check the firmware version. Make sure the firmware you downloaded is for your TV model, for example, the firmware for the Mi TV 4S 55 won't work for the Mi TV 4A 43.
4. Update via OTA. If the USB flash drive update doesn't work, try updating through the TV menu: Settings → About TV → System Update.

If the TV after a failed update does not turn on or stuck on the logo, try resetting it to factory settings:

1. Turn the TV off the socket.
2. Press and hold the Menu button on the remote (or on the back of the TV).
3. Connect the power without releasing the button for 10-15 seconds.
4. In the recovery menu, select Wipe data/factory reset.

What do you do if nothing helps?

If you’ve tried all the ways but the “Unacceptable Signature” error still appears, the problem may be deeper:

• 🔧 Recovery or boot is damaged, and only flashing through Fastboot or EDL (emergency mode) will help. EDL requires a special cable and Mi Flash Tool.
• 🔒 The device is locked by the operator. Some smartphones sold through carriers (e.g. MegaFon or Beeline) have additional locks. In this case, contact the operator for unlocking.
• 🛠️ Hardware malfunction: If the error occurred after a fall or moisture, the device memory (e.g., eMMC chip) may have been damaged.

To diagnose hardware problems, you can use service codes:

• Enter the number of the dialer: ##4636## (information about the system).
• For memory check: ##36446337## (eMMC test).

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If the device does not turn on or freezes on the logo after a signature error, DO NOT try to re-stitch it without diagnosis. This may aggravate the problem.

How to avoid the “unacceptable signature” error in the future?

To avoid this problem, follow simple rules:

• 📥 Get firmware only from official sources. Avoid torrents and questionable sites. Better use Xiaomi Firmware Updater or official portal MIUI.
• 🔄 Update via OTA if possible. Automatic Over-The-Air updates minimize the risk of errors as files are checked by Xiaomi servers.
• 🔓 Don't install custom firmware without experience. If you're a beginner, it's best to use official software. Custom firmware requires unlocking the bootloader and can lead to a loss of warranty.
• ⏳ Don't interrupt the update process. If the device is being updated, don't turn it off and remove the flash drive/cable. This can damage system files.
• 📡 Check the stability of the Internet connection. If the signal is weak Wi-Fi or mobile network, the firmware file can download with errors.

If you still decide to experiment with custom firmware, make a habit:

• 📝 Make backups via TWRP or Mi PC Suite.
• 🔧 Check firmware compatibility with your model in forums (e.g., XDA Developers).
• 🛡️ Use antivirus to check downloaded files.

FAQ: Frequent questions about the "Impermissible Signature" error