FP3: Unable to update from 1.5q-dev to r-stable - "Failed to find update binary"

[AnotherElk]

@Asperamanca

Just when I gave up all hope, I just wanted to reboot my device from Fastboot, and instead got onto an e Recovery screen. There I could select “Apply update” - “Apply from ADB”, which sounded just like what I want, but wasn’t covered in the instructions I had found so far. But in that mode, my PC would suddenly see the device.

However, trying to install the 1.6-r-stable image via that mode failed (“Signature verification failed”). Overriding that led to “Failed to find update binary” on the phone.

There are FP3 documentation problems caused by dev and stable builds coming in different formats currently.
dev builds get installed via ADB sideload (the way you tried), but stable builds get flashed with fastboot while the phone is in fastboot mode.
Here are instructions which currently apply to stable builds …https://doc.e.foundation/devices/FP3/install.

Fairphone - FP3 - FP3+ Documentation Suggestions

The command line install instructions given at Install /e/OS on a Fairphone FP3/3+ - “FP3” are currently only valid for the stable install files, not for the dev install files. The stable install files currently come in the format which installs partition images with fastboot, the command line install instructions cover this. The dev install files currently come in the OTA format ready for use with ADB sideload in the recovery, the command line install instructions don’t reflect this at all as…