I'm looking for a way to install a flashable zip (no OTA zip), using the "Install Update from SD card" option built into any stock recovery, without installing a custom recovery. Is there any way to do this? Will "unlocking OEM" in developer settings allow this?

  • A stock recovery is engineered to only accept .zip files signed by the OEM. You can try to flash something else, but the process will likely be halted.
    – Grimoire
    Jul 18, 2019 at 19:27
  • the answer is no. unlocking will not change the behaviour of stock recovery. what you can do is boot into custom recovery from PC via fastboot without flashing it.
    – alecxs
    Jul 18, 2019 at 20:44

1 Answer 1


Unfortunately this is not possible on devices newer than Android 5.0.

After 5.0, signature verification was enhanced to combat the Universal Signature bug.

Prior to Android 5.0, a bug existed in the Signature verification program, something to do with the way the signature was validated allowed another signature to result in the same validation ( The Universal Signature ) .

To answer your question for Android 5.0 and lower..

  • Repackage the custom system.img into an OTA Update format

  • Sign the update package with the Universal Signature

  • Hope that it validates through the stock program.

In most cases, the recovery program checks the format and signature are correct, then it check's if the package is designed for your device by reading the build.prop.

If your build.prop matches the package, and the signature is validated it will install.

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