Develop Bugs

[Q] Attempting to Update: libwebrtc_audio_preprocessing.so

I'm trying to update to 4.1.2 and I'm getting "apply_patch_check("system/lib/libwebrtc_audio_preprocessing.so" as not being the original file.
I have no idea what changed that or how I can return it to normal. Any ideas?

Not enough information.
Was your phone completely stock and unaltered before you tried going to 4.1.2? What method are you using to get to 4.1.2?

garyd9 said:
Not enough information.
Was your phone completely stock and unaltered before you tried going to 4.1.2? What method are you using to get to 4.1.2?
Click to expand...
Click to collapse
I was on stock, then used CF-AutoRoot. Pretty much nothing besides that. According to other threads, if I used voodoo OTA and just unfreeze the AT&T apps it should work, it has for them.
Would this be due to some other root app?

OmegaNemesis28 said:
I was on stock, then used CF-AutoRoot. Pretty much nothing besides that. According to other threads, if I used voodoo OTA and just unfreeze the AT&T apps it should work, it has for them.
Would this be due to some other root app?
Click to expand...
Click to collapse
Okay.. so you were NOT completely stock. You also didn't mention what method you used for the update. Was it pushed to you over the air, or did you download it and copy it to your phone?
If you are following instructions from other threads on the update, then you might consider posting this question on one of those other threads.
I can tell you what *I* did, but I won't support that: I used ODIN to get my phone 100% back to stock (ODIN to replace the stock firmware/kernel/recovery, factory reset to erase the phone) and then installed the update via external SD. After the update was installed, I used ODIN to replace recovery, and then used that recovery to re-root and restore my backups.
Take care
Gary

garyd9 said:
Okay.. so you were NOT completely stock. You also didn't mention what method you used for the update. Was it pushed to you over the air, or did you download it and copy it to your phone?
If you are following instructions from other threads on the update, then you might consider posting this question on one of those other threads.
I can tell you what *I* did, but I won't support that: I used ODIN to get my phone 100% back to stock (ODIN to replace the stock firmware/kernel/recovery, factory reset to erase the phone) and then installed the update via external SD. After the update was installed, I used ODIN to replace recovery, and then used that recovery to re-root and restore my backups.
Take care
Gary
Click to expand...
Click to collapse
Sorry.
And no, I guess not completely stock. Just CF-AutoRoot.
I tried both OTA update and copying the update to my /cache and using ODIN. Where is where I was getting the error.
If I flash back to stock and don't factory reset/erase my phone, would this still fix any modded files like audio_preprocessing in my /system/? Flashing back to a stock ROM won't erase my apps/settings correct? I'm still pretty new to this.
What backup method did you use? ADB nandroid or something like Titanium?

OmegaNemesis28 said:
I tried both OTA update and copying the update to my /cache and using ODIN. Where is where I was getting the error.
Click to expand...
Click to collapse
That statement is confusing. You got the error trying the OTA or when updating via a manual copy to /cache?
OmegaNemesis28 said:
If I flash back to stock and don't factory reset/erase my phone, would this still fix any modded files like audio_preprocessing in my /system/?
Click to expand...
Click to collapse
If you flash back to stock via ODIN, it should completely rewrite everything in /system to revert it back to factory (as well as unroot your device.)
OmegaNemesis28 said:
Flashing back to a stock ROM won't erase my apps/settings correct? I'm still pretty new to this.
Click to expand...
Click to collapse
It shouldn't, but that doesn't mean it won't. That's why I'm a big fan of backing things up.
OmegaNemesis28 said:
What backup method did you use? ADB nandroid or something like Titanium?
Click to expand...
Click to collapse
I have an external memory card and use TWRP (replacement recovery) to backup. I ALSO backup with titanium backup pro to the external sdcard.
Gary

Help! Accidentally hit the OTA upgrade while runing TWRP (bootloop)

I hit the "OK" on the OTA box without thinking, and only realized my mistake when TWRP came up after it started it's process.
I can get all the way back into the Launcher, but after about 60 seconds is reboots.
I'm guessing all I need to to undo one thing, or maybe flash a new/stock bootloader, but I don't really know where to start. I am coming from Samsung phones, so the terminology is rather different with HTC.
I've already made a backup of boot, system, and data, from within TWRP and copied it off the phone. I also quickly moved the OTA zip off my phone as well in order to keep a copy of it. Lastly, I can boot into "Safe Mode" (which I discovered by accident) and it doesn't do the reboot thing.
Any help at all is appreciated.
Thank you.
EDIT: Success!
Turns out I needed to re-flash my SuperSU binary from TWRP. I re-flashed the version I had first which actually removed the SuperSU apk. I re-downloaded it from Play Store, then flashed the 2.01 update. Runs like a charm.
Thanks to everyone for the help.

Hi,if you already backup your ROM before OTA,just restore it

hdorius said:
Hi,if you already backup your ROM before OTA,just restore it
Click to expand...
Click to collapse
I only did the backup after I got into the reboot cycle.
I haven't tried restoring it, but I don't imagine that it will work.

Can u please post your cid?u can find the stock nandroid backup that linked at my signature

winnower said:
I only did the backup after I got into the reboot cycle.
I haven't tried restoring it, but I don't imagine that it will work.
Click to expand...
Click to collapse
No it will not work. Just delete the backup and save you the time and trouble messing with it. If you can grab a good backup from someone then you will be ok. Simply restore and all should be well. Then, make sure you remove your custom recovery prior to accepting the OTA.
---------- Post added at 07:44 AM ---------- Previous post was at 07:42 AM ----------
Another method you could do would be to heavily modify the updater-script within the OTA. Removing the checks should suffice and thereby allow you to install the OTA via your custom recovery but it is easier said than done lol. A lot of lines to go through.

hdorius said:
Can u please post your cid?u can find the stock nandroid backup that linked at my signature
Click to expand...
Click to collapse
Ok, I need to do a bit of reading it seems.
I installed TWRP and SuperSu, but didn't modify my CID or get S-OFF (yet). I have a Bell Mobility version if that helps.
Modding.MyMind said:
No it will not work. Just delete the backup and save you the time and trouble messing with it. If you can grab a good backup from someone then you will be ok. Simply restore and all should be well. Then, make sure you remove your custom recovery prior to accepting the OTA.
---------- Post added at 07:44 AM ---------- Previous post was at 07:42 AM ----------
Another method you could do would be to heavily modify the updater-script within the OTA. Removing the checks should suffice and thereby allow you to install the OTA via your custom recovery but it is easier said than done lol. A lot of lines to go through.
Click to expand...
Click to collapse
Thanks, I kinda figured the backup wouldn't help.
I would at least like to be able to restore the /data partition to keep my apps and such. I assume the /data backup I made after ****ing this thing up will not work for restoring /system files, but my data does matter to me.
I looked into the OTA zip file and found a /firmware.zip/recovery.img file. Will that recovery image work?

winnower said:
Ok, I need to do a bit of reading it seems.
I installed TWRP and SuperSu, but didn't modify my CID or get S-OFF (yet). I have a Bell Mobility version if that helps.
Thanks, I kinda figured the backup wouldn't help.
I would at least like to be able to restore the /data partition to keep my apps and such. I assume the /data backup I made after ****ing this thing up will not work for restoring /system files, but my data does matter to me.
I looked into the OTA zip file and found a /firmware.zip/recovery.img file. Will that recovery image work?
Click to expand...
Click to collapse
Just use the command "fastboot getvar all" it will read your CID and find the backup at Stock Nandroid Backup that match your phone and restore it
Edit: oops the thread that i linked is closed and all the links are removed

winnower said:
Ok, I need to do a bit of reading it seems.
I installed TWRP and SuperSu, but didn't modify my CID or get S-OFF (yet). I have a Bell Mobility version if that helps.
Thanks, I kinda figured the backup wouldn't help.
I would at least like to be able to restore the /data partition to keep my apps and such. I assume the /data backup I made after ****ing this thing up will not work for restoring /system files, but my data does matter to me.
I looked into the OTA zip file and found a /firmware.zip/recovery.img file. Will that recovery image work?
Click to expand...
Click to collapse
The recovery image is based for the new OTA. Won't necessarily be the same as what your device currently used but it should still work. If by any chance it does not then it is because of the Bootloader version you are currently running which is causing the problem. Which at that point you will need to grab the other stock recovery.img prior to the update.
---------- Post added at 09:56 AM ---------- Previous post was at 09:55 AM ----------
I don't have your device so I can't really provide any links to assist even further but I ca build you a foundation to go off of. The logic with this stuff is relatively universal across common android devices for the most part.

winnower said:
I looked into the OTA zip file and found a /firmware.zip/recovery.img file. Will that recovery image work?
Click to expand...
Click to collapse
Since you have the OTA, can you put the details of android-info.txt that you have inside it ?? This will definitely help you to find the right recovery/backup.

Modding.MyMind said:
Another method you could do would be to heavily modify the updater-script within the OTA. Removing the checks should suffice and thereby allow you to install the OTA via your custom recovery but it is easier said than done lol. A lot of lines to go through.
Click to expand...
Click to collapse
Have you actually seen this done? AFAIK stock recovery is required to install OTA; but perhaps I'm mistaken. In any case, its far easier to restore stock recovery if the intent is to install OTA. However, the current installed ROM must also have no system files altered, as this is also a requirement for OTA installation.
Another (probably easiest) way out of this loop would be to mount the memory, find the OTA file and delete it. The phone should then stop trying to find stock recovery to install the OTA (which is the cause of the bootloop).

@redpoint73, that is a valid question to ask. I have not seen any guides made available to the public however, I can vouch it works. I once did it myself many many many months ago once I did some extensive studies on how an OTA was applied. Though, I won't hesitate to mention that it's a tedious process and I wouldn't recommend it less it were your only absolute option since there are so many easier methods to use.

Modding.MyMind said:
@redpoint73, that is a valid question to ask. I have not seen any guides made available to the public however, I can vouch it works. I once did it myself many many many months ago once I did some extensive studies on how an OTA was applied. Though, I won't hesitate to mention that it's a tedious process and I wouldn't recommend it less it were your only absolute option since there are so many easier methods to use.
Click to expand...
Click to collapse
Good to know, thanks for the explanation. Interesting that custom recovery will actually work (technically) with an OTA, that its just security checks that keep if from happening.
As you mentioned, there are many much easier options to recovery; so what you mentioned is just a method of "last resort".

ckpv5 said:
Since you have the OTA, can you put the details of android-info.txt that you have inside it ?? This will definitely help you to find the right recovery/backup.
Click to expand...
Click to collapse
OTAfile/firmware.xip/android-info.txt:
modelid: 0P6B16000
cidnum: BM___001
cidnum: SASKT001
mainver: 2.23.666.2
btype:1
aareport:1
hbootpreupdate:12

hdorius said:
Just use the command "fastboot getvar all" it will read your CID and find the backup at Stock Nandroid Backup that match your phone and restore it
Edit: oops the thread that i linked is closed and all the links are removed
Click to expand...
Click to collapse
Ok, downloaded fastboot-win.zip from HTC's dev site.
C:\Android\m8>fastboot getvar cid
cid: BM___001
finished. total time: 0.000s
So, if those links are offline, do you have another source or just use the one I got with the OTA?

Did you try to just find the OTA file and delete it, as I previously suggested? This should get the bootloop to stop.

redpoint73 said:
Did you try to just find the OTA file and delete it, as I previously suggested? This should get the bootloop to stop.
Click to expand...
Click to collapse
Yes, the OTA is no longer on the phone.
It's not really "bootlooping", it boots normally into the Sense launcher, then after about a minute it restarts. It's not stuck on the HTC logo or anything; it's more like a restart-cycle.

Were you on a stock ROM, or custom before this OTA mess started? My recommendation would just be to pick a custom ROM of your choice on the phone (either via adb push or on the removable SD) and flash it in TWRP and forget this OTA business. Making it more complicated than it needs to be, and OTAs don't really have any business on modded phones anyway, for the most part.

redpoint73 said:
Were you on a stock ROM, or custom before this OTA mess started? My recommendation would just be to pick a custom ROM of your choice on the phone (either via adb push or on the removable SD) and flash it in TWRP and forget this OTA business. Making it more complicated than it needs to be, and OTAs don't really have any business on modded phones anyway, for the most part.
Click to expand...
Click to collapse
I was on stock Sense6. I had previously unlocked and loaded TWRP since I assumed I'd switch ROMs very shortly after getting the phone. I was coming from Samsung's world where running my own ROM was mandatory since TouchWiz was so awful.
The only thing keeping me from flashing a custom ROM right now is my data/apps. In my sleep deprived state, I didn't think to make a backup (or to not accept the OTA in the first place). If I can flash a customized Sense6 ROM and keep my apps/data then I will.

The phone isn't really working for more than a minute or so. So I'd just do a wipe and install a custom ROM. Something is broken now, so a clean slate is probably your best bet.

Yeah, I'm just trying a few last things.
I tried flashing the newest TWRP and the stock recovery.img I got with the OTA; no luck.
I still have the full OTA zip though... Is there any way for me to adb push that file on the /sdcard/ to force it to complete the update? That way I can just re-flash TWRP and SuperSu and keep my data.
Thanks for all the help.

LG G4 problem with stock reset

Hello,
Everyone I have a problem with my LG G4. I rooted it a few months ago and now I ran into a problem so I decided to do a factory reset in hopes to get a clean stock version. After the phone was cleaned off I noticed that Super SU was still installed which I thought was weird so I checked the rooted status and it was still rooted. I have no idea how it could still be rooted after a factory reset. I want to do all the updates for the phone and re-root it again but it is stuck being root at the moment.
So I found this guide --> [Guide] LG G4 Stock Firmware (Go Back to Stock) KDZ & TOT Method.
I couldn't get this flash kit to work on my G4. I have tried it on a Windows 10 laptop and windows 7 laptop to see if there was a difference and still no luck.
Does anyone have any other methods of resetting an LG G4?
Thanks everyone

Just download the kdz you need and flash it using this tool. Works 100%. Cheers

Follow_and_Feel said:
Just download the kdz you need and flash it using this tool. Works 100%. Cheers
Click to expand...
Click to collapse
Does it matter that it is a verizon with vs98611a?

If you still have the backed up system.img (before rooted), you can flash it back like you did to root. Please read in the low effort root thread how to backup system.img (before root) and to restore it. I also ran into this problem, supersu couldnt be full unroot and I had to restore the backed up system.img (since I didnt have the kdz).

hikku13 said:
If you still have the backed up system.img (before rooted), you can flash it back like you did to root. Please read in the low effort root thread how to backup system.img (before root) and to restore it. I also ran into this problem, supersu couldnt be full unroot and I had to restore the backed up system.img (since I didnt have the kdz).
Click to expand...
Click to collapse
Thanks for the information. I am new to this and did not back up my system. Does anyone have a clean KDZ for verizon VS98611A? What's the best way to restore the backup?

Terrofmen said:
Thanks for the information. I am new to this and did not back up my system. Does anyone have a clean KDZ for verizon VS98611A? What's the best way to restore the backup?
Click to expand...
Click to collapse
Just search along XDA. Actually you can find everything yourself if you do a proper search.
Check this.
And please hit thanks, if I helped
Cheers

HTC 816G downgrade from lolipop to kitkat

hi
i had to root my htc 816g after the lollipop update cuz the small internal memory size and i couldn't even update the soft apps
i used TWRP
i just want to downgrade it to kitkat with the right steps and the right stock
i want to be able to apply the official updates too so can i or i will never be able to since i rooted it before ?!
i don't have enough info about rooting or backing up so pls try to explain

ShakeItBaby said:
hi
i had to root my htc 816g after the lollipop update cuz the small internal memory size and i couldn't even update the soft apps
i used TWRP
i just want to downgrade it to kitkat with the right steps and the right stock
i want to be able to apply the official updates too so can i or i will never be able to since i rooted it before ?!
i don't have enough info about rooting or backing up so pls try to explain
Click to expand...
Click to collapse
I have the 816 a5_chl single SIM version but let me try to help you because I'd like to. First I believe the rooting methods for your device is a bit different then the one for mine so bear with me here. First I would advise against going backwards to kit Kat from lollipop. Lollipop returned the write permissions to the external SD card for apps that were taken away with kitkat and that's just for starters. Lollipop has battery and performance improvements as well. As for doing stock updates you would need to find and reflash your stock recovery back as well as remove any root exploits from your firmware before any signed stock updates could be performed. What was the root method you used on your model ? Mine was to unlock boatloader thru HTC, flash TWRP recovery and from that recovery flash SuperSU zip file from internal storage of phone.
As for backing up you would first run a backup from TWRP to your ext SD card called a full nandroid backup which is basically a snapshot of your whole phone as it is before you flash any other firmware. Enable compression and leave the MD5 check enabled then name your backup and select micro SD card as the location then swipe to run. Titanium Backup app is used to back up apps and data along with texts and call logs. Google's own backups can be setup from your phone settings and back up your contacts and phone numbers mainly. Super Backup app can also back up your calender as well as texts, call logs, etc.... I use all 3 myself plus the TWRP backup that you can restore if something gets messed up and it often can.

thoctor said:
I have the 816 a5_chl single SIM version but let me try to help you because I'd like to. First I believe the rooting methods for your device is a bit different then the one for mine so bear with me here. First I would advise against going backwards to kit Kat from lollipop. Lollipop returned the write permissions to the external SD card for apps that were taken away with kitkat and that's just for starters. Lollipop has battery and performance improvements as well. As for doing stock updates you would need to find and reflash your stock recovery back as well as remove any root exploits from your firmware before any signed stock updates could be performed. What was the root method you used on your model ? Mine was to unlock boatloader thru HTC, flash TWRP recovery and from that recovery flash SuperSU zip file from internal storage of phone.
As for backing up you would first run a backup from TWRP to your ext SD card called a full nandroid backup which is basically a snapshot of your whole phone as it is before you flash any other firmware. Enable compression and leave the MD5 check enabled then name your backup and select micro SD card as the location then swipe to run. Titanium Backup app is used to back up apps and data along with texts and call logs. Google's own backups can be setup from your phone settings and back up your contacts and phone numbers mainly. Super Backup app can also back up your calender as well as texts, call logs, etc.... I use all 3 myself plus the TWRP backup that you can restore if something gets messed up and it often can.
Click to expand...
Click to collapse
first thx for reply
so if i just wanna stay with lolipop and just unroot it what should i do
i used TWRP and i backed up my rooted system days ago
i tried many times to unroot using the unroot option in supersu but nothing happened
so could u pls tell me the steps
like what stock i should download and how to install it ?!

ShakeItBaby said:
first thx for reply
so if i just wanna stay with lolipop and just unroot it what should i do
i used TWRP and i backed up my rooted system days ago
i tried many times to unroot using the unroot option in supersu but nothing happened
so could u pls tell me the steps
like what stock i should download and how to install it ?!
Click to expand...
Click to collapse
Your welcome. Ok, you did good by doing a TWRP backup first. You'd be surprised how many people don't so kudos for that. Second you shouldn't need to find a stock zip firmware file to download as long as your system is pure stock and you've reflashed your stock recovery for your model phone. Those are usually found either here in XDA linked or you just have to try to enter your model found listed in your hboot or in settings under about phone. Once you've verified the correct stock recovery zip file you download it to your P.C.s ADB/fastboot folder and flash it over TWRP then relock your boatloader. Some say they can flash stock updates with it unlocked but most recommend you relock it for it to work. From there assuming the unroot method has worked you should be able to do stock updates from your phone or over a computer using HTCsync assuming nothing else was altered in your firmware system from stock.
You say that unrooting thru SuperSU hadn't worked. How do you know that? Have you used a root checker from the play store to verify? It should work because he wrote that into his app specifically to unroot for stock updates or to use someone else's superuser app.
Also what was your rooting method? I believe your phone is the Mediatek version and the Snapdragon processor in my version had a different root exploit or an extra step from my exploit to get a foothold in your system as the processor is different from mine. You would need too remove that exploit as well I believe as it probably altered some system files to allow SuperSU to use it's exploit to gain root permissions.
Found this link below on the web but can't vouch for whether it works or not.Also search here in XDA forums for unroot method as this link says it compiled the info from XDA. Remember you'll still need your stock recovery reflashed before your can do a stock update as this refers to just unrooting.
http://android-unroot-guide.xyz/htc-desire-816g-dual-sim/

Is there an easy way to update an unlocked/rooted Pixel 3a XL?

I unlocked my bootloader and rooted my Pixel 3a XL as soon as I got it. But I've been unable to install the OTA and security updates since (September 2019). I've been digging around in the forum trying to figure out how to load the updates. I was really hoping Flashfire would work, but it gives me errors - something about the root not being available or right... but my root works for everything else I've tried (maybe its an issue with Magisk)...
Anyway, I was hoping to find a simple way to install the updates. Help!
Thanks in advance,
Tom

Tom2112 said:
I unlocked my bootloader and rooted my Pixel 3a XL as soon as I got it. But I've been unable to install the OTA and security updates since (September 2019). I've been digging around in the forum trying to figure out how to load the updates. I was really hoping Flashfire would work, but it gives me errors - something about the root not being available or right... but my root works for everything else I've tried (maybe its an issue with Magisk)...
Anyway, I was hoping to find a simple way to install the updates. Help!
Thanks in advance,
Tom
Click to expand...
Click to collapse
I have seen postings about people fastboot flashing back the original boot.img, then taking the ota then repatching the new boot image and flashing it via fastboot. Not as simple as you hoped i am sure but it works.
The other way is to download the full image, remove the -w option in the flashsall.bat and then run the modded flashall file. You then need to patch the new boot image as above and fastboot flash that to regain root. I have not found any other ways to get updates besides doing one of the 2 above every month

Thanks, adm1jtg! I appreciate the help.
Unfortunately, I tried the second method you mentioned on my own... but I missed the part about removing the -w from the flashall.bat. Faaaaaaaaaaaqqqqqqqq!!! And ended up wiping my phone.
But now I think I'll remember that -w trick! I love learning things the hard way. LOL
I'm still going to hold out hope that someone will come along and make an app like FlashFire to script the process for us.

Tom2112 said:
Thanks, adm1jtg! I appreciate the help.
Unfortunately, I tried the second method you mentioned on my own... but I missed the part about removing the -w from the flashall.bat. Faaaaaaaaaaaqqqqqqqq!!! And ended up wiping my phone.
But now I think I'll remember that -w trick! I love learning things the hard way. LOL
I'm still going to hold out hope that someone will come along and make an app like FlashFire to script the process for us.
Click to expand...
Click to collapse
Why wouldn't you just side load the OTA and be done with it?? Easy instructions where you'll download the OTA image. Easier than what your currently doing

thatsupnow said:
Why wouldn't you just side load the OTA and be done with it?? Easy instructions where you'll download the OTA image. Easier than what your currently doing
Click to expand...
Click to collapse
Sideloading the ota would be a great option EXCEPT he said he was on a much older version... Like sept.
My understanding is that the ota for dec would only contain changes implemented for the month of December, this in this scenerio he would not get the patches for October and November with your method and i am not even sure if it would boot after that mismatch
It's really not saving much work if any over flashing the full version, and with the full version they're is no potential for bootloop due to missing some patches or updates. It's just much safer.

thatsupnow said:
Why wouldn't you just side load the OTA and be done with it?? Easy instructions where you'll download the OTA image. Easier than what your currently doing
Click to expand...
Click to collapse
Um... prolly because I'm dumb... and maybe a little because I couldn't find instructions on how to do it properly. I don't suppose you happen to have a link to how to do the OTA sideload thing properly?

Tom2112 said:
Um... prolly because I'm dumb... and maybe a little because I couldn't find instructions on how to do it properly. I don't suppose you happen to have a link to how to do the OTA sideload thing properly?
Click to expand...
Click to collapse
https://developers.google.com/android/ota

The most simple way to update while keeping root would be to follow the instructions for "Devices with A/B Partitions" at the following link in the Magisk documentation:
https://topjohnwu.github.io/Magisk/tutorials.html#ota-installation
Basically, Magisk allows you to restore the original boot image to the current partition so you can take the OTA when it arrives on your phone. Before rebooting you install Magisk to the inactive slot so that when the phone restarts you retain root without having to mess with Fastboot.

Delete Me!
Think all you have to do is click uninstall magisk, dont reboot... Take ota, but before reboot click install magisk/ install to empty slot...
Oops didnt see the reply above

OK, so when this month's security update came out, I tried to following the Magisk instructions (uninstall Magisk, restore stock boot, flash OTA, etc...) but when I went to uninstall Magisk and restore the stock boot, it tells me there is no stock boot image to restore! Dammit. Now what?

Tom2112 said:
OK, so when this month's security update came out, I tried to following the Magisk instructions (uninstall Magisk, restore stock boot, flash OTA, etc...) but when I went to uninstall Magisk and restore the stock boot, it tells me there is no stock boot image to restore! Dammit. Now what?
Click to expand...
Click to collapse
This should be a one time issue. One of the latest versions of Magisk changed the default location of the boot.img backup. They released it in December after most of us had already upgraded to the December Pixel update. This means we used the older version of Magisk when we installed the Dec update and it saved the backup to the old/original location. We then updated Magisk sometime later in December, but the Magisk update doesn't move the backup file to the new location (a poor execution from the Magisk team IMHO). Because we are now on the updated version, it expects the boot.img backup to be in the new location, but it is still in the old location and Magisk doesn't check that old location (again, a poor execution from the Magisk team IMHO).
To fix this you have several options.....
Option one is to find the original backup location that Magisk used for the boot.img and move it to the new backup location that Magisk uses. Unfortunately, I don't know where those backup locations are and didn't feel like researching it, so I used one of the other methods.
Option two is to "reinstall" Magisk (choose the patch file option and select the stock boot.img that may still on the phone from whatever the last update was (if you sideloaded the update and then had to rerooted the phone)- or download it from the applicable factory image and move it to the phone) to force Magisk to backup the current boot.img file to the new location. Stop after this initial step (ie you don't actually need to flash the patched file because it has already been done). Then you should be able to follow the normal Magisk update process to move to the January update.
That being said, I have horrible success being able to take the updates OTA (they usually fail) and usually end up sideloading the update. That is the final option - sideload the Jan update and then reroot the phone using the normal root method (ie getting Magisk to patch the stock boot.img file and then flashing the patched file).