The HTC ROM Update Utility (RUU) is an official Windows-based software tool used to flash a complete, stock firmware package onto HTC Android smartphones. It restores the device to a factory state, including the operating system, radio, bootloader, and recovery partition. RUUs are critical for system recovery, official OS upgrades, and returning to stock software.
Running an RUU formats the device. It does not preserve user data (photos, contacts, apps).
HTC officially stopped providing RUU downloads on their website around 2018. Today, finding an RUU requires visiting community archives like: htc android phone rom update utility
Because HTC no longer signs new RUUs, devices with S-ON (Security On) cannot flash unsigned custom RUUs. If you plan to modify a legacy HTC phone, achieving S-OFF (using tools like revolutionary, rumrunner, or SunShine) is essential—it disables signature checks and allows you to flash any ROM.
Even with careful preparation, errors happen. Here are the most frequent issues: The HTC ROM Update Utility (RUU) is an
| Error Code | Message | Solution |
|------------|---------|----------|
| Error 170 | USB Connection Error | Reinstall HTC drivers. Try a different USB port (USB 2.0 preferred). Use a shorter cable. |
| Error 155 | ROM Version Mismatch | Your bootloader is unlocked or you have a custom ROM. Relock the bootloader: fastboot oem lock. |
| Error 140 | Bootloader Version Error | The RUU is older than your current bootloader. You cannot downgrade without S-OFF. |
| Error 132 | Signature Error | The RUU is not intended for your device (wrong MID/CID). Double-check your model. |
| Error 171 | USB Connection Lost | The USB cable was disconnected during flash. Try a different PC or disable USB selective suspend in Windows Power Options. |
| Stuck at 0% / 1% | — | Your phone has S-ON (security on) and the RUU isn’t signed for your CID. You need S-OFF or an RUU with matching CID. |
The Ultimate Fix for Persistent Errors: Extract rom.zip from the RUU, rename it to PH85IMG.zip (or the appropriate code for your model, e.g., PG76IMG.zip for the Desire HD), place it on the root of a FAT32-formatted microSD card, and boot into HBOOT. The bootloader will automatically detect and flash the file—bypassing many Windows driver issues. Because HTC no longer signs new RUUs, devices
Veteran HTC users remember “HBOOT” (the bootloader) and the “FASTBOOT USB” prompt. The RUU is essentially a graphical front-end for fastboot commands. Behind the scenes, the RUU executes commands like:
fastboot oem rebootRUU
fastboot flash zip rom.zip
fastboot reboot
Understanding this is valuable because:
Some developers convert official RUUs into ZIP files flashable via TWRP recovery. This preserves user data and doesn't require a PC.