[HTC Desire 601] Vency77:
What you found is actually something different, nothing to do with OTA. Personally I updated my zara_ul yesterday which was heavily modded, and everything went well, here are some things to keep in mind when updating (whatever you do is your responsibility, so really - THINK before doing anything!).

First of all, I suggest you to S-OFF before updating, it doesnt hurt and could eventually save you a lot of headaches if something goes wrong. I wont give steps for obtaining S-OFF cuz you can find them like 10 times in this thread.

Make some kind, if not every kind, of backup - TWRP, Titanium, Contacts, SMS's, whatever. You might not need them, but its better to have them, isnt it?

The OTA doesnt require you to be relocked, but if you are S-OFF, when you restore the /system, you will be in bootloop because of the hcheck file, so the only choice is to relock it.

Now there are many, many scenarios that may vary from user to user. The most important thing is to have your /system partition to be like the day you bought the phone. By this I mean everything - every ****ing app to be restored, everything new to be removed(su binay and su application for example), evey font you changed to be returned to stock, return hcheck file if you have deleted it, xposed deleted, every mod reversed, and actually EVERYTHING. Kernel (boot.img) should be stock, not jmz's, not unsecured, not whatever, but the stock one. And last, you will need the stock recovery.

The best way to do this if you have a completely stock reovery backup of the /system partition (before rooting) and just restore it. Then flash the stock kernel (again hopefully you have backed it up, otherwise find it here for your version - UL or CL). Then flash the stock recovery.

If you dont, you can try manually restoring what you have altered in /system, but there is a chance of forgetting something. Other way is to restore someone else's stock backup, but if the carriers are different then most likely the /system partitions differ a bit. Here again dont forget to restore kernel and recovery.

The easiest way - run a RUU and then everything will be stock. But then again comes the many scenarios part - if the RUU is for different carrier, then you have to flash ENG Hboot(firewater), then change CID and MID to match the ones for the RUU, so that you can get the OTA (and actually flash the RUU).

If the update goes all right, you will have everything running stock and KK. To root it, and obviously to flash a recovery, for you CL users I wont give any advice until the update is out. When it is, we should see the partition table info and then decide if the recoveries made till now will work okay and then rooting is easy.

For the people that

know what they are doing

and for the UL users, here is mostly-working TWRP(credits to whoever made it and hosts it, I think its [MENTION=5209254]standak14[/MENTION] ), and there is a Philz CWM for KK too, for which I can give you a link.

Keep in mind that the speakers volume is really lower on KK, you can try removing the battery for like 5 minutes and then it should be better, but I didnt found difference. However, after some reboots and as sometime passed, I think that the volume restored almost as before, but IDK really :laugh:

Thats all I can advice you off top of my head, but really there are many scenarios, and many IF's... You better read some pages around here and the net, then ask if you need or dont know something, hopefully I or someone else here can help you :cowboy: