LG Flash Tool: What It Is & How to Use It (2025 Guide)

Part 1. What Is LG Flash Tool?

LG Flash tool is a Windows program used to install official LG firmware (KDZ or TOT files) on LG phones and tablets. It’s mainly used to update or downgrade the software, fix devices stuck in a boot loop, or bring a non-working (bricked) device back to life.

Part 2. When Do You Need LG Flash Tool?

You might need the Flash Tool for LG devices in scenarios such as the following:

• Stuck on Boot Screen/Bootloop: Caused by failed updates, corrupt files, or incorrect rooting.
• Failed OTA Update: Install official LG software (KDZ/TOT files), especially when OTA updates fail due to power loss or bad internet.
• Custom ROM or Malware Issues: Problems from custom ROMs, system corruption, or unwanted changes.
• Software Bugs or Downgrade Needs: Issues like lag, battery drain, or missing features after an update.
• FRP Lock Bypass (Limited Cases): In some cases, flashing firmware can help bypass Factory Reset Protection.
• Unbrick Devices: Restore phones stuck in Download/Emergency Mode or not turning on.
• Factory Reset: Erase all data and do a clean software install to fix serious issues or remove malware.

Part 3. LG Flash Tool Download & Detailed Guide [2025 Latest Versions]

LG software download requires you to get its compatible version from a safe site and also download the required drivers. You can get three types of LG Flash tool:

• LG Flash Tool 2014: For older models like LG G3, G4, V10.
• LG Flash Tool 2.0.2.5 (2025): Newer version with bug fixes for recent phones.
• LGUP: Modern tool for LG devices running Android Marshmallow and up (e.g., G5, V20, G7).

Where to Download Safe Versions?

You can download LG Flash Tool 2014 from sites like AndroidFileHost (direct, no ads) or LO4D (virus-tested). The 2025 version is available on LG-Flash.com (looks official, but double-check safety) and Mobofiles (virus-checked). For newer devices, LGUP is recommended, with patched versions found on GizDev or in an XDA thread that also bypasses login.

Compatibility

The LG Flash tool 2024 supports Windows 7/8/10 (not XP), its 2025 version is compatible with Windows 10/11, and the LGUP tool works on Windows 8/10/11.

Required Drivers & Files

Here are the drivers and firmware files you’ll need to download to run the LG Flash tool or LGUP software:

• LG USB Drivers: Get from LG’s official site or included with LGUP.
• ADB & Fastboot Drivers: Needed for advanced tasks.
• MegaLock.dll: Required for older versions of LG Flash Tool.
• Firmware Files (KDZ/TOT): Found on LG-Firmwares.com (official) or XDA Forums (user uploads) and must match your phone’s exact model (e.g., H830 for LG G5).

LG Flash Tool Step-By-Step Guide

Here’s how to flash LG phone with LG flash tool (2014 and 2025) and LGUP:

• LG Flash Tool (2014)
  • Step 1: On your Windows computer, you’ll need to download drivers and LG Flash Tool 2014 (from AndroidFileHost). Also, get the correct KDZ firmware for your model (e.g., D855 for G3) and Visual C++ Runtime (if the tool crashes).
  • Step 2: Turn off your LG phone. Then, press and hold “Volume Up” and plug in the USB until “Download Mode” appears.
  • Step 3: Run “LGFlashTool2014.exe” as Admin. Then, choose “Type” as “CDMA” (even for GSM phones) and “Phone Mode” as DIAG.
  
  • Step 4: Click the folder icon and pick your “.KDZ” file. Pick a flash method:
  • Normal Flash: Keeps data (not ideal for serious issues).
  • CSE Flash: Wipes all data (best for bootloops or errors).
  • Step 5: To start flashing on your LG device, tap “Start.” Then, choose a language (default: English). Wait for it to finish (don’t unplug).
  • Step 6: Your LG phone will restart automatically. First boot may take over 10 minutes.
• LG Flash Tool (2025)
  • Step 1: You’ll need drivers, LG Flash Tool 2025 (from lgflash.com, and MegaLock.dll (replace in the tool folder if needed). Also, get the KDZ firmware. It supports large KDZ/TOT files (over 1GB
  • Step 2: Then, enter “Download Mode” on your LG phone and connect to your PC using the same method as mentioned in “LG Flash Tool 2014.”
  • Step 3: Run the LG Flash tool. There’s no LG Mobile Support tool or extra files required. Next, load the KDZ/TOT firmware and choose a flash type.
  • Step 4: Follow the on-screen instructions and start flashing on your LG phone. There’s no need for a server or login.
• LGUP Flash Tool
  • Step 1: You’ll need a patched LGUP (from XDA), KDZ firmware, and required DLL files (place in: C:\Program Files (x86)\LG Electronics\LGUP\model).
  • Step 2: Then, enter “Download Mode” on your LG phone and connect to your PC using the same method as mentioned in “LG Flash Tool 2014.”
  • Step 3: Execute LGUP. Then, choose a flash mode:
  • Upgrade: Keeps data.
  • Refurbish: Full wipe (best for fixing major issues).
  
  • Step 4: Tap “Browse.” Then, select your KDZ file to load. Start flashing on your LG phone.
  • Step 5: Wait for it to finish. Your LG phone will reboot automatically.

Part 4. LG Flash Tool vs LGUP Tool

Here’s a clear table comparing LG Flash Tool and LGUP Tool, showing the main differences in what they do, their compatibility, and how to use them:

Please swipe to view

Part 5. Common Errors & Troubleshooting For LG Flash Tool

While flashing your device with an LG Flash tool, you might come across frequent issues. Here are the common errors and their solutions:

Stuck at 0%, 2%, 4%, or 9% During Flash

Use a USB 2.0 port and reinstall the LG drivers, and on Windows 8/10/11, disable driver signature enforcement. Make sure the KDZ/TOT file matches your exact phone model (e.g., D855 for LG G3). If problems persist, try using 32-bit Windows, like Windows 7 x86. Use LG Flash Tool 2025 or LGUP to avoid freezing issues.

“Wrong DLL” Error

Replace the “MegaLock.dll” file in the LG Flash Tool folder. For LGUP, make sure the correct model DLL files are in:

C:\Program Files (x86)\LG Electronics\LGUP\model

USB Connection Not Recognized

Open Device Manager. If you see an exclamation mark, set the COM port to COM41 and reinstall the latest LG USB drivers. If that doesn’t help, try using a different cable or PC, as some issues like LG Flash tool connection to server failed can fix themselves this way.

Flashing Fails Mid-Process

If you face an error like the “LG Flash tool cannot run this program” or the flashing procedure fails midway, switch off the antivirus or firewall. They might block the flashing process. Also, try using “CSE Flash” instead of “Normal Flash” to fully rewrite everything and avoid errors. If the firmware file seems corrupted, download it again.

Preventing Bootloop After Flashing

Use “CSE Flash” for major updates, downgrades, or region changes, as it does a full wipe. Keep your USB and power connection stable to avoid interruptions and after flashing, do a factory reset in Recovery Mode (wipe cache and data).

Part 6. Best Alternative For Fixing LG System Issues (No Flashing Needed)

If you don’t want to flash manually or find the steps too complicated or risky, Tenorshare ReiBoot for Android is the best alternative to repair LG systems without flashing. It also doesn’t require rooting, downloading KDZ/TOT firmware, placing the LG phone in Download Mode, or technical skills to fix the issues. Moreover, ReiBoot for Android offers:

• Can repair and fix 50+ issues on Android devices, including an LG phone stuck on the logo, in a boot loop, or on a black screen.
• Can fix freezing issues on LG devices or the phone not switching on.
• Allows you to enter/exit Recovery Mode, Download Mode, and Fastboot Mode in a single tap.
• Clear system cache on Android devices in a single tap.
• Supports popular Android brands like LG, Samsung, Huawei, OPPO, OnePlus, etc.
• Supports all Android versions up to 16.

Here’s how to fix issues on your LG phone with ReiBoot for Android:

• Download ReiBoot for Android on your computer. Then, connect your LG phone to the same computer via USB.

• Choose “Repair Now” on the interface.

• Enter your device information correctly, then click Next. Download the correct firmware package. It will take a few minutes.

• After downloading, click "Repair Now" to start fixing your phone.</p>

• Once the repair is successful, there will be a confirmation message on your computer. Click Done and disconnect your phone.

Conclusion

The LG Flash tool and LGUP are useful for fixing LG phones by flashing firmware which is great for bootloops, failed updates, or bricked devices. Just make sure to use the right drivers, firmware, and a stable connection. LGUP is easier to use than LG Flash tool, especially for newer models.

If you don’t like manual steps or flashing feels too complicated, Tenorshare ReiBoot for Android is a simpler and automatic option. It can fix 50+ system problems like boot loops, stuck on the logo, or black screens without needing flashing firmware or technical steps. It’s also faster, supports all popular Android brands, and can fix problems in Android versions from 5 up to 16.

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