[0xndc]

It's a check - as of Android 5.0, Google's OTA updater scripts refuse to overwrite your /system partition if its checksum isn't on the known-good list. Rooting inevitably involves writing files to it, so OTA updates will stop working with an uninformative "Error!" in recovery. Whoever came up with the idea should be fired, but that's Google for you.

See [1] for details from the author of NRT [2], which can update your phone from factory images without wiping it. The procedure is a bit more involved if you're not on Windows - IIRC, you have to download the correct archive from [3] and modify the update script so it doesn't try to flash userdata.

[1] http://www.wugfresh.com/faqs/can-i-still-take-an-ota-after-i... [2] http://www.wugfresh.com/nrt/ [3] https://developers.google.com/android/nexus/images

[NeutronBoy]

> Whoever came up with the idea should be fired, but that's Google for you.

To be fair to Google, once you've modified your /system partition, it's really case-by-case how an update will interact with it. The alternative is Google push an update that inadvertently bricks a bunch of rooted phones. Can you imagine the kneejerk reaction from the internet then?

[nadams]

> The alternative is Google push an update that inadvertently bricks a bunch of rooted phones. Can you imagine the kneejerk reaction from the internet then?

That already happens [1] on non-modified devices. So just come up with a "yes I know what I'm doing and accept that this may bork my phone". Or and even better idea - how about the ability to turn off OTA updates? Right now my phone says there is an update but I can't apply it due to being rooted.

[1] http://www.techtimes.com/articles/51525/20150508/nexus-9-and...