Updated to 4.2.19, doesn't come up?

There is a problem with directly updating from that firmware to 4.2.19 (this issue has been solved in 4.2.20).

Here's a good solution if you have a spare disk (must not be from your array): http://www.readynas.com/forum/viewtopic.php?p=340135#p340135

If you don't have a spare disk, contact tech support (http://www.readynas.com/support). They should be able to downgrade the firmware for you so you can get the unit back into a working state.

Thank you, Thank You!, THANK YOU!!!

I'd noticed the upgrade through frontview didn't work--but it did not display any warning either--didn't think much of it, READ THE RELEASE NOTES, downloaded and did the deed. Which killed it dead.

So per your advice I put in a drive that was sitting around, came up (yay!) as corrupted root, did the reset to factory defaults secret handshake, put on .17, once it was happy put my disks back in and it was happily running .17 (with all my settings intact), upgraded to .19 and all is well.

So again, THANK YOU! But why the hell didn't Netgear pull this or make note of the problem?

Not sure why they didn't make a note of the problem in the release notes.

The issue is fixed in 4.2.20.

If you updated via System > Update > Remote it would have suggested updating to 4.2.16 then after updating to that it would have suggested updating to 4.2.19.