Database Info

Dalvik-cache

so I cleared my dalvik-cache this morning. first i tried doing it in RA-1.5.2 or whatever, it said it failed. So, then i booted the phone up, adb shell'd into it and did a
Code:
rm -r /data/dalvik-cache
now when I boot up I get a ton of FC's (literally, i get 2000, i counted) They seem mostly to be Sprint, but there are also some google stuff, and some other random ones. The reason I cleared it was to try to reclaim some free space, for some reason I'm around 30mb free on Settings->SD and Phone Storage, after clearing I'm still only around 55. Trying to find the culprit.
BTW: I do have a nandroid from last friday, but I consider that to be a last resort :-/

this problem has come up before seems the best thing to do is reflash whatever rom your running over itself and that seems to fix it.

The recovery doesn't clear the boot cache. You can use the fresh kitchen it has the option to clear cache in the tools and tweak menu..
That worked for me yesterday when this exact thing happened.

@wtphoto i'm running stock sprint, will reflashing it format it and get rid of my stuff?
@thedudejdog do i have to have fresh on my phone to do this?

You did it wrong.
Why were you trying to do this, and what instructions were you following?

That command didn't delete the entire cache folder as well did it?
Like as in you didn't delete the actual folder, just the insides right?

@jonnythan
http://forum.xda-developers.com/showthread.php?t=537830
The reason I cleared it was to try to reclaim some free space, for some reason I'm around 30mb free on Settings->SD and Phone Storage, after clearing I'm still only around 55. Trying to find the culprit.
Click to expand...
Click to collapse
@willowmp
no, the folder is still there and there are dex files in it
EDIT: after reboot, the files are there

Code:
rm -r /data/dalvik-cache
You erased the folder itself, not just the contents of it. Someone who's actually tested will have to speak up and tell us whether Android is smart enough to recreate the folder if something/someone deletes it.
EDIT: Ah, I see someone HAS tested that and Android will recreate it.
The reason I cleared it was to try to reclaim some free space, for some reason I'm around 30mb free on Settings->SD and Phone Storage, after clearing I'm still only around 55. Trying to find the culprit.
Click to expand...
Click to collapse
Why is 30 mb a bad number?

idk, i always see people saying they have 100+ free, and for a few months I had ~70, then all the sudden it dropped to ~30

If you remove the dalvik-cache, you have to also remove the boot-cache at the same time to avoid the FCs.
But if you remove the dalvik-cache and boot-cache, they get recreated the next time you boot up. It will "save" space, but the cache directories will just get filled right back up.
As far as I can tell, the only reason to ever delete these caches is if you're having some sort of error/FC condition.

thanks for the fix jonnythan and thedudejdog, clearing boot-cache seemed to have fixed the FC's. All except google voice it seems, but I've always had a boot FC on GV. thanks for the help

[Q] rooting, battery drain, and SD Card issues

So I have my new verizon SG3, and I wanted to root it to have access to the SD card. As I seem to have already filled up my storage.
So I started reading many threads, starting with this one for Jelly bean:
http://forum.xda-developers.com/showthread.php?t=2046439
I had trouble with the custom recovery stage. ODIN kept failing when trying to flash it. So eventually I came with a prerooted stock flash at this link:
http://forum.xda-developers.com/showthread.php?p=33948598
and that seems to have got me to root status.
Now I am not really sure what I need the custom recoveries for, or if this link includes the boot loader or unlocker, or whatever it is, and if I really need it.
I'm looked at various ROMS and haven't really seen anything I think I need.
All I really want to do is have access to my SD card which I thought I had with the root option. But any apps that I say "Move to SD card" they only move to the internal SD card and not external.
How Do I actually use my external card?
Also, I have noticed that every time I turn the screen on, I see the "preparing SD card" message on the notification bar. and sometimes a message saying it has been removed.
What's going on with that?
And finally, my battery has been draining rather quickly. "MEDIA" seems to be using about 70% of the battery.
This is including two instances of Downloads
com.sec.android.providers.downloads
DRM protected content storage
and media storage
I read somewhere that it may be unwise to delete the preinstalled content, so I tried freezing the DRM as another forum stated that was ok as well as media hub, some of the google apps, and the verizon ringtones.
But in that process, I somehow managed to loose my notifications and ringtone selections, and when I try to reinstate them, it shows unknown ringtone, and the only options when I click to change is my GO SMS and Solid Explorer. I did locate the ringtones in the systems folder, but clicking on them only gives me an error.
I'm not sure how to get the standard selection screen back.
I tried flashing the previous stock rom again, but that did not help any.
So the question is, how do I get things back to working again, while still being rooted? Then how do I get true access to my SD card? And what can I safely remove. If a ROM will accomplish all this, which one is best and easiest to install?
I already used up half my data usage for the month installing all my apps, so I'd prefer not to do anything that would make me have to go through all that again. I have ROM toolbar installed, but it doesnt seem to want to let me do a backup. (I may need a recovery if I can get that working this time)

update
Update:
I managed to get the CWM recovery flashed finally.
How do I know if my bootlocker is unlocked if I installed the prerooted jelly bean rom I linked to before?
I also managed to get the ringtone selection to work again. I had the Media service frozen still. But that was what I think was a big battery drainer, so we will see. Im not sure why it would be draining the battery so much, something is going on.
I'm still having issues with the SD card, and installing anymore apps even after I deleted a few of the big ones. I was going to install a battery calibration tool witch is less than 200 kbs and it still is showing insufficient storage. Let the drive doesnt seem full. Maybe this is a partition issue? If so, how do I verify that and change it?

Ez unlocker in the play store will unlock your bootloader if you are rooted.
Volume up the phone before clicking yes. ;]…
One thing I've always stuck to, if it's messed up, go back to the beginning.
Could be md5 of dl or build of rom/packing of .tar, flash, etc.
Flash pure motives rls 13, works great.
Sent from my SCH-I535 using xda app-developers app

jam.i.s0n said:
Ez unlocker in the play store will unlock your bootloader if you are rooted.
Volume up the phone before clicking yes. ;]…
Sent from my SCH-I535 using xda app-developers app
Click to expand...
Click to collapse
Nah bud, EZ Unlock v.1.2 will properly get you unlocked, it's available on rootzwiki.
Sent from my SCH-I535 using xda app-developers app

Ok, so I am unable to install any apps now no matter what I uninstall. I'm getting an insufficient storage error now, yet I seem to have plenty of space. This is getting really annoying.
I bought the SD card for apps to save their data to it, yet all apps save to the internal SD CARD, and not the external. I see a few apps i can download to possibly switch this option, but I really shouldnt have to go through all that. Whats the point of having a SD card in the first place if no app uses it.
Regardless, something is messed up. Battery is still draining like crazy which seems to be a common problem, but I have yet to find a fix. I would consider a factory reset, but I need to figure out how to back up first, as I can not afford to go and reinstall all my apps again. Will the back up preserve all my apps and their settings without having to reinstall from the play store? I have less than a GB of data left and I'm only about 6 days in my plan.
I am trying to drain my battery completely now, to see if that may "reset" its calibration or whatever. I'm not sure how that works, but It was suggested in places, so I'm trying.
What are my options for a full data wipe? and what is the best way to get my apps back without using a lot of data to do so? I tried doing a backup with my rom toolbox pro last night but I don't believe it worked. I dont think my phone is connecting to my external SD card. I can see the data on it if I browse, but no app actually saves anything onto it. Also, the phone wont let me delete, rename, paste, or do anything accept maybe open files from the card. I had it reformatted to FAT32 before I loaded anything onto it. So I'm not sure the issue. If Its protected, I'm not sure how to unlock it as micro cards dont have he lock switches like the big ones (which was a whole other issue for me when connecting to my computer)
Any advice? I know I'm not the only one with these issues.

So I am still having insufficient space errors when trying to download apps, though for some reason I did manage to get one random app installed that was in my "All apps" section from my previous phone.
I have tried wiping catch, and dalvik, and battery stats. That did nothing.
I have also tried reflashing the unlocked jelly bean update, with no results.
I think a full wipe may work but once again, since I can't make a back up since I can't install the apps to do so. I'm a bit reluctant to do this because I don't want to have to reinstall everything again and use more of my data connection. I do have a wifi connection, but I'm not sure I want to risk that not working properly.
Is there a way to manually backup my apps and data? what should I make copies of?

internal storage full

I'm running [GT-P31XX][JB][4.2.2] CyanogenMod 10.1, just fyi
So all of a sudden I can't install any more apps... it keeps saying internal storage full.
I've even uninstalled all the "extra's" I've been running.. I went from like 150 or more apps installed down to (what I consider) hardly any and it just keeps saying it.
It's not talking about the internal SD card is it? I have almost a gig or room on that.
I'm at a loss here.
Any apps to clear my memory or something? I've used Allininetool, doesn't help, SDMaid, doesn't help... a couple other that I can't remember the names of, they didn't help either.
bleh!
Thanks i advance for any help.

donniegalaxy2 said:
I'm running [GT-P31XX][JB][4.2.2] CyanogenMod 10.1, just fyi
So all of a sudden I can't install any more apps... it keeps saying internal storage full.
I've even uninstalled all the "extra's" I've been running.. I went from like 150 or more apps installed down to (what I consider) hardly any and it just keeps saying it.
It's not talking about the internal SD card is it? I have almost a gig or room on that.
I'm at a loss here.
Any apps to clear my memory or something? I've used Allininetool, doesn't help, SDMaid, doesn't help... a couple other that I can't remember the names of, they didn't help either.
bleh!
Thanks i advance for any help.
Click to expand...
Click to collapse
same issue is there in my aunts tab 2..on doing a factory reset..all is fine, but after a month only having a bunch apps (consuming max 1gb space), it shows that there is no space! (but doing a factory reset again solves the problem)
planning to take it to the service center!

peRFect! said:
same issue is there in my aunts tab 2..on doing a factory reset..all is fine, but after a month only having a bunch apps (consuming max 1gb space), it shows that there is no space! (but doing a factory reset again solves the problem)
planning to take it to the service center!
Click to expand...
Click to collapse
I reflashed the rom and cleared cache and dalvik. seems to be ok now but thats curious as to why it happens.

Can't tell you why this happens and After trying to install some large games and apps i ran in to this. I didn't know that you could only install to the internal SD otherwise i would have got the 16GB version.
After a lot of searching i came across this in the general section, it (so far) has worked like a dream for me.
http://forum.xda-developers.com/showthread.php?t=1961097
[EDIT] This only works on 4.1.x versions.

Actually there is no need to reflash ROMs or even factory reset. I have read about such problems and they are usually related to cache. I do not know the exact name or type of cache which cause the problem, but I recall 2 solutions:
1) Install either Quick System Info Pro or ES Task Manager. Use the 'Clear cache' function inside these apps then restart device.
2) If you do not like to install these apps, then you can boot into Recovery mode & select "Clear cache' from the recovery menu.
I have read these solutions on several forums, including here at XDA Developers. I am not certain if they will work as I myself have not encountered such problems. Maybe if anyone does & needs help, do feel free to try these solutions?

S8+ factory reset, wiped micro SD card

Hi all, I have had my S8+ for several months now, everything was fine until this morning when I woke up to unlock my phone, it unlocked as per normal. I enabled wifi and opened google chrome and checked the weather. The, the phone shutdown and within a few seconds the blue screen appeared with a message (erasing). It took a while for the phone to boot up and go through the initial setup like a brand new phone.
Now, all the data on the phone and my 32GB micro SD card are gone. I have tried half a dozen recovery software on my PC but none can see any files on the micro SD.
I have no idea what happened and why it has wiped the micro SD card. I have lost images and videos of the last few years, I know silly not to have them backed up.
Any help will be greatly appreciated.

Wow, that is a great disappointment losing all that personal info. I suspect you are running a recovery software app from a PC or a Mac? If you are not getting any meaningful results from the data restore apps, and you know those apps to be of good/high reputation, then I am wondering of your phone uses a type of 'wipe' function that performs a military/DOD sort of erase?
If that is the case, that stuff is likely gone forever. If that is not the case, hopefully you can find another app to try and restore your stuff.
Now, on the other note, that's an odd behavior for your phone to just reboot and do it's thing, wiping your system. Do you have any type of security going where it might have thought the phone had been stolen, and performed a wipe as protection for the owner. . . (you)?
Good luck.

I do have company email on my phone and I have agreed to their security policy which wipes all your data. This could be one of the reason, however could they erase data from SD card?
I had over 60GB of personal files on it and I thought the SD card will not get wiped in any case.
I have been reading around but can't find any solution. Stuffed to the max.

gunner007dc said:
You can check the phone's memory - sometimes it has a "SD RESTORE" folder if it backed up anything.
By chance is this a company phone, or had a company e-mail on it? Sometimes those e-mails require device administrator and can be remotely wiped.
Click to expand...
Click to collapse
Good info.

gunner007dc said:
You can check the phone's memory - sometimes it has a "SD RESTORE" folder if it backed up anything.
By chance is this a company phone, or had a company e-mail on it? Sometimes those e-mails require device administrator and can be remotely wiped.
Click to expand...
Click to collapse
Thanks, where would I find this folder? I have checked by can't find it.

Not a screen of death but maybe a glimpse of it

My Note20U5G has had this small glitch for a while:
When I am using it, especially it I am opening an app window or typing inside one, EVERYTHING on my screen disappears for like 1 second. The only thing left is the homescreen wallpaper (without icons on it) and after that 1 second everything comes back to normal, if I was typing the screen where I left of, I am taken back to continue typing, etc... Now, even though this happens only once or up to twice a day, I figured it could be a sign that something is wrong.
So what I did was, is that I deactivated all apps that (in my opinion) could've contributed to this; onehand operation plus, live wallpapers, some apps in the background such as wireless power sharing, that I really never use.
However, no help. The twice a day glitch continued.
Next, I wiped cache using the "safe mode" or whatever it is called. I did this 2 days ago. And yesterday the whole day phone operated without glitches. But as day passed today I got one again.
As I am clueless what to do next I figured to do a hard reset, that is set the phone to factory settings.
Since I've owned this phone since November, there's some preparation to do before reseting to factory settings, so I thought to ask you guys if someone else had this glitch, as I was unable to google for it.
Thanks

Looks like a system UI crash and spontaneous recovery.
Do you have any apps put to sleep /standby or enlisted in deep sleep esp system apps
Also do you have power saving turned on.
Any thing that you changed in developers options.
I would update my phone to latest firmware and factory reset it.
Update all apps
Report back with an update

fizzingbees said:
Looks like a system UI crash and spontaneous recovery.
Do you have any apps put to sleep /standby or enlisted in deep sleep esp system apps
Also do you have power saving turned on.
Any thing that you changed in developers options.
I would update my phone to latest firmware and factory reset it.
Update all apps
Report back with an update
Click to expand...
Click to collapse
Nope, I don't have power saving on.
Here are my deep sleep apps. Nothing worth mentioning there IMO, all of them are some apps I might use but I don't ever need them running in the background.
If I go for factory reset, what is the best way to do it and no lose any personal data by chance. Obviously, I would back up photos to my computer... But other than that, what should I be careful about?

Try clearing the system cache.
Factory reset time, may be malware or maybe the OS or a vital system apk got corrupted.
Almost always caused by a 3rd party app especially launchers.
You got an SD card slot, use it!
It's a data drive; you have a dual drive PC
OS, download folder and apps go on internal storage.
Critical data, user files, music, vids, DCIM (move images here once a week or so) and backup copies of apps, app settings backup, phone contact backups, etc go on the SD card.
Use ApkExport to copy all your apps... no Playstore needed for a reload.
Everything you need for a full restore should be on the SD card. Think it through completely to avoid unpleasant surprises.
The Lexar 512 gb V30 card works well $75.
Other cards may be faster; only use a name brand card with at least a V30 rating.
Note: backup the SD card to at least 2 hhds that are physically and electronically isolated from each other!

blackhawk said:
Try clearing the system cache.
Factory reset time, may be malware or maybe the OS or a vital system apk got corrupted.
Almost always caused by a 3rd party app especially launchers.
You got an SD card slot, use it!
It's a data drive; you have a dual drive PC
OS, download folder and apps go on internal storage.
Critical data, user files, music, vids, DCIM (move images here once a week or so) and backup copies of apps, app settings backup, phone contact backups, etc go on the SD card.
Use ApkExport to copy all your apps... no Playstore needed for a reload.
Everything you need for a full restore should be on the SD card. Think it through completely to avoid unpleasant surprises.
The Lexar 512 gb V30 card works well $75.
Other cards may be faster; only use a name brand card with at least a V30 rating.
Note: backup the SD card to at least 2 hhds that are physically and electronically isolated from each other!
Click to expand...
Click to collapse
LoL I didn't know there was a memory slot, didn't need to think about it since I switched from a 128gb phone to this 256gb. Yeah, gonna get an sd card. Thanks

vdamir78 said:
LoL I didn't know there was a memory slot, didn't need to think about it since I switched from a 128gb phone to this 256gb. Yeah, gonna get an sd card. Thanks
Click to expand...
Click to collapse
Yeah once you get use to it, you'll demand it.
All my PCs and laptops are dual drive. It saves a lot of time, pain and boosts performance.
I can do a full reload on my Note 10+ in about 2 hrs and have it back to about 99% fully operational with no internet connection.
Without the card it becomes a gruelling 8+ hour process including having to load over 240 gb of data.
Backup everything now as once an Android OS starts exhibiting instability it's one boot away from a boot loop☠
They are very rare but that's how they start many times

Alright, I have just done one more thing: I completely disabled Nova Launcher (stopped using it anyways after I bought this N20U). If that doesn't help, I am proceeding with the reset.

vdamir78 said:
Alright, I have just done one more thing: I completely disabled Nova Launcher (stopped using it anyways after I bought this N20U). If that doesn't help, I am proceeding with the reset.
Click to expand...
Click to collapse
The Samsung launcher is better anyway, rock solid stable, fast with little battery usage.
Clear the system cache.
A 3rd party launcher can definitely crash a Samsung. One boot looped my Note 10+ twice, back to back over a year ago. I was seeing red.
Still running on the OS from that 2nd reset... still fast and stable less the 3rd party launcher

No essential app in deep sleeping apps.
Boot to safe mode and see if the problem persist, otherwise it's one of your apps responsible for this anomaly.
Copy entire internal drive data to SD card it flash drive via otg adapter
Use smart switch to backup Samsung notes.
Use swift backup or alpha backup app for contacts logs, messages and apps ( external data not saved fully on non-root devices)
Backup whatsapp on Google drive.
Afterwards, either flash factory firmware via odin to completely remove all traces of bugs ( recommended, use csc instead of home csc to wipe internal storage and all data)
Or factory reset from settings.
Then boot to recovery and wipe internal storage +factory reset again.. Its a bit extra but would eliminate any software related issues.
Report with update

blackhawk said:
The Samsung launcher is better anyway, rock solid stable, fast with little battery usage.
Clear the system cache.
A 3rd party launcher can definitely crash a Samsung. One boot looped my Note 10+ twice, back to back over a year ago. I was seeing red.
Still running on the OS from that 2nd reset... still fast and stable less the 3rd party launcher
Click to expand...
Click to collapse
I have seen this issue with good lock app on my note 4.. Uninstalling it caused system ui to crash repeatedly making phone unusable

vdamir78 said:
Alright, I have just done one more thing: I completely disabled Nova Launcher (stopped using it anyways after I bought this N20U). If that doesn't help, I am proceeding with the reset.
Click to expand...
Click to collapse
That's strange.
I have been rocking nova launcher since completing setup wizard. No issues so far.

fizzingbees said:
I have seen this issue with good lock app on my note 4.. Uninstalling it caused system ui to crash repeatedly making phone unusable
Click to expand...
Click to collapse
Wonder if it was the Lockstar module?
I never use any apps like that... once bitten, twice shy Other than it's goofy lame main page Good Lock gives me zero issues.
It wasn't Nova that boot looped the 2 OSs
It was slower and used more battery though then One UI... Samsung has made big improvements to their native launcher. The most customizable stock Android platform in existence too. It runs very well, uses very little power and is rock solid stable at least on my Note 10+/Pie variant. It has never crashed.

blackhawk said:
Wonder if it was the Lockstar module?
I never use any apps like that... once bitten, twice shy Other than it's goofy lame main page Good Lock gives me zero issues.
It wasn't Nova that boot looped the 2 OSs
It was slower and used more battery though then One UI... Samsung has made big improvements to their native launcher. The most customizable stock Android platform in existence too. It runs very well, uses very little power and is rock solid stable at least on my Note 10+/Pie variant. It has never crashed.
Click to expand...
Click to collapse
Actually it was 2017 version of Samsung good lock app that changed the lockscreen and quick panel.
Not like the modules now.

Update:
I decided to go for a samsung microsd, but I had to order a 256gb on ebay. So while I am waiting for it, I disabled good lock (nicelock to be precise) and I completely uninstalled Nova launcher.
No glitches since then.

Update:
After going back & forth with sd card purchase for my phone, I finally got a 256gb sd card that is the same size as my note20ultra's internal memory. So I was thinking, is it possible to completely mirror the phone's storage to sd card, and after I factory reset the phone, to copy that mirror back to the phone.
I used to do this with some PCs at my work a long time ago, using some sort of "ghost software"... so anyways, my sd card is capable to take every single data from the phone, what is my best backup/restore option to go for after a factory reset?
(Btw, the problem that I described in the opening post still persists, however it has become less frequent, like 50% less of a "hiccup" than it used to be)

vdamir78 said:
(Btw, the problem that I described in the opening post still persists, however it has become less frequent, like 50% less of a "hiccup" than it used to be)
Click to expand...
Click to collapse
Which OS and Samsung UI are installed on your N20U?
Are any applications listed in your Care report "Application history" in the Samsung Battery and device care section?
I had major "issues" with the System UI crashing after updating to Android 11/One UI 3.0 until the bugs were fixed with an update.
Surely hope you find a fix and do not have to factory reset your phone.

vdamir78 said:
Update:
After going back & forth with sd card purchase for my phone, I finally got a 256gb sd card that is the same size as my note20ultra's internal memory. So I was thinking, is it possible to completely mirror the phone's storage to sd card, and after I factory reset the phone, to copy that mirror back to the phone.
I used to do this with some PCs at my work a long time ago, using some sort of "ghost software"... so anyways, my sd card is capable to take every single data from the phone, what is my best backup/restore option to go for after a factory reset?
(Btw, the problem that I described in the opening post still persists, however it has become less frequent, like 50% less of a "hiccup" than it used to be)
Click to expand...
Click to collapse
I don't know of any app that can mirror Android drives real time. That not to say there isn't.
You would definitely take a performance hit if you could do it.
Like I said before the best solution is to use the SD card as the data drive. Just make sure to backup it up redundantly.
The lag your describing is bothersome. Track it down. It may be malware.
Clear system cache and do a hard reboot.
Do a network reset and clear the sim card tool kit data. Toggle Developer options off to clear it's settings... you can reenable then.
Disable all animations.
Is it still there?
Does it happen in safe mode?
If a 3rd party app is the cause either correct it or uninstall the app.
If you can't resolve the issue consider it malware and do a factory reset.
See if it's there after the reset before loading apps. If still present reflash the firmware.
If still present it may be a hardware issue.
This phone should be rocket fast with no lag.
There's near zero lag on my 10+ which has a slower memory and CPU.

blackhawk said:
I don't know of any app that can mirror Android drives real time. That not to say there isn't.
You would definitely take a performance hit if you could do it.
Like I said before the best solution is to use the SD card as the data drive. Just make sure to backup it up redundantly.
The lag your describing is bothersome. Track it down. It may be malware.
Clear system cache and do a hard reboot.
Do a network reset and clear the sim card tool kit data. Toggle Developer options off to clear it's settings... you can reenable then.
Disable all animations.
Is it still there?
Does it happen in safe mode?
If a 3rd party app is the cause either correct it or uninstall the app.
If you can't resolve the issue consider it malware and do a factory reset.
See if it's there after the reset before loading apps. If still present reflash the firmware.
If still present it may be a hardware issue.
This phone should be rocket fast with no lag.
There's near zero lag on my 10+ which has a slower memory and CPU.
Click to expand...
Click to collapse
The problem is that it is so random. I could not pinpoint any app to relate to it. I unistalled some apps in the meantime, but it still persists (less frequent). If I restarted in safe mode I would probably have to keep the phone in safe mode for at least 3 days to be sure.
Is there a malware detecting antivirus for android that works efficiently?

vdamir78 said:
The problem is that it is so random. I could not pinpoint any app to relate to it. I unistalled some apps in the meantime, but it still persists (less frequent). If I restarted in safe mode I would probably have to keep the phone in safe mode for at least 3 days to be sure.
Is there a malware detecting antivirus for android that works efficiently?
Click to expand...
Click to collapse
Reload time if the steps I mentioned don't work or if you did a major firmware upgrade without a factory reset.
Malwarebytes is good but there are always new undetectable infections floating around.
With odd behavior that cause can't be determined a virus or rootkit is a real possibility. They are very rare if you're careful but can happen.
I caught a trojan preloader on my 10+ about a year ago in the download folder with Malwarebytes. Fortunately I found/deleted it before it could download it's payload package and install it. It self downloaded through the Samsung browser... a nasty little bugger.

Malwareb. detected one malware app today, some photoediting app...deleted it, so let's see...