Windows 10 Windows 10 startup error 0xC000021A

[jeyem]

So yesterday i shut down my computer, and today when i started it up (about 2 hours ago) i can see the startup Motherboard message and all the BIOS stuff, but after that it is just a blank black screen, can't see the blue Windows logo, or that spinning circle indicating that it's loading. I don't even see my mouse cursor.

Now i would try it in safe mode but for reasons unknown you can't get to Windows 10 safe mode without getting first to the desktop, which i obviously can't right now.

I would try the repair installation tool, but after i boot from USB device with the install media, then i get the Windows logo and the loading circle, but after that it just ends up in a screen that says "Your PC ran into a problem we will restart it now" and with a small white text it reads error 0xC000021A.

(It doesn't say the 0% complete thing but other than that its all the same)

So any ideas guys? Was there some update that messed it all up? I didn't see any message saying installing updates or anything like that when i shut the PC down. Could it be that it installed something in the background or is my PC bust?

 

[kemical]

Hi,
if you can get to the lock screen, then if you hold down the shift key and then with the mouse click restart. This should in theory get you into safe mode but obviously all depends on whether you have access to the lock screen (where you input your password).
If you do have the install media on USB you can change the boot options so that you boot straight from the USB device but instead of doing a clean install access the repair environment. I know you say you tried this above but at what point does the error come up?

 

[big black]

Hi, I'm new here so I don't know if this is appropriate but here goes. I have the same problem as the OP. I tried shutting down my pc but got a pop up saying windows is downloading updates. Anyway after this finished my pc will not work. I am in a loop going round and round but never getting into my pc. I have tried everything I can find on the internet and maybe some things I shouldn't have done but I am two doors away from putting this laptop in the bin and starting again. Nice thought but what about all my work... not backed up... silly me. Can anyone offer a solution other that the bin tia

 

[Neemobeer]

You should be able to get to safe mode. While the computer is starting hold shift and tap F8

• Troubleshooting
• Advanced
• Start computer in safe mode
• Reboot
• If it loads then you probably have a driver problem.

You may also want to try running a repair on the boot process from the shift + F8 menu
bootrec /rebuildbcd

 

[Emily Forbes]

Hey,
This BSOD error is caused due to damaged winlogon.exe and csrss.exe files. Try the following to resolve the issue.

Restart PC using shift and restart option
Option screen will appear, select troubleshoot option
Now go to advanced options
Go toStartup Settings> Disable driver signature enforcement(press F7).
PC will start with the selected option
Hope it will be helpful

 

[alfreed]

Hey,
This BSOD error is caused due to damaged winlogon.exe and csrss.exe files. Try the following to resolve the issue.

Restart PC using shift and restart option
Option screen will appear, select troubleshoot option
Now go to advanced options
Go toStartup Settings> Disable driver signature enforcement(press F7).
PC will start with the selected option
Hope it will be helpful

____________________________________________________________________________________________________________________
Windows 10
my laptop keep showing the error 0xc0000021a and restart again and again is like a loop..i unable get into the desktop screen
even using USB boots up startup repair all not working.

 

[kemical]

Windows 10
my laptop keep showing the error 0xc0000021a and restart again and again is like a loop..i unable get into the desktop screen
even using USB boots up startup repair all not working.

This bugcheck is usually caused by mismatched system files. You need to change your boot order so that you can boot from USB that contains either the recovery media or Windows 10.
Beginner Geek: How To Change the Boot Order in Your Computer’s BIOS
Once you get into the recovery section using the USB then you can try either system restore or a RESET:
Recovery options in Windows 10 - Windows Help

 

[Plance]

So yesterday i shut down my computer, and today when i started it up (about 2 hours ago) i can see the startup Motherboard message and all the BIOS stuff, but after that it is just a blank black screen, can't see the blue Windows logo, or that spinning circle indicating that it's loading. I don't even see my mouse cursor.

Now i would try it in safe mode but for reasons unknown you can't get to Windows 10 safe mode without getting first to the desktop, which i obviously can't right now.

I would try the repair installation tool, but after i boot from USB device with the install media, then i get the Windows logo and the loading circle, but after that it just ends up in a screen that says "Your PC ran into a problem we will restart it now" and with a small white text it reads error 0xC000021A.

(It doesn't say the 0% complete thing but other than that its all the same)

So any ideas guys? Was there some update that messed it all up? I didn't see any message saying installing updates or anything like that when i shut the PC down. Could it be that it installed something in the background or is my PC bust?

 

[Plance]

Got the same error message and endless loop trying to repair pc -- thought I was going to have to replace computer. Then found the Microsoft link for creating a Windows 10 recovery disk that has to be made on another computer. Produced the disk but then had to change the boot order in my computer's bios file so that DVD drive opened before hard drive. When setup began had to do advanced setting to reinstall Windows 10. Temporarily lost all old files/folders but you can find them in Windows.old and reinstall.

 

[Anderson443]

Hey,
This BSOD error is caused due to damaged winlogon.exe and csrss.exe files. Try the following to resolve the issue.

Restart PC using shift and restart option
Option screen will appear, select troubleshoot option
Now go to advanced options
Go toStartup Settings> Disable driver signature enforcement(press F7).
PC will start with the selected option
Hope it will be helpful

I did this and it solved my problem. What does disabling driver signature enforcement do? Is there anything else I need to do? This doesn't look like something that would fix the problem. The other two options that I haven't tried yet are the recovery disk and system image.

 

[kemical]

What does disabling driver signature enforcement do

When drivers are created they need signing off by Microsoft to say they've been tested and work. So when a driver hasn't got the signature it's considered beta and usually that's the only difference between a driver being beta or Whql, the signature.
Disabling sig' enforcement means your system will now run beta files without needing a Microsoft signature first.

 

[Anderson443]

What will happen if I re-enable it? I'm not sure what happened by disabling signature enforcement that fixed the issue.

A windows page says the error can be caused by CSRSS.exe or winlogin.exe failing to work or mismatched files. I'm thinking it's the latter. I searched my event viewer for the time I first encountered the error. Here it is:

Log Name: Application
Source: Microsoft-Windows-CAPI2
Date: 7/13/2016 9:01:06 PM
Event ID: 513
Task Category: None
Level: Error
Keywords: Classic
User: N/A
Computer: MATTS-PC
Description:
Cryptographic Services failed while processing the OnIdentity() call in the System Writer Object.

Details:
AddLegacyDriverFiles: Unable to back up image of binary Microsoft Link-Layer Discovery Protocol.

System Error:
Access is denied.
.
Event Xml:
<Event xmlns="Link Removed">
<System>
<Provider Name="Microsoft-Windows-CAPI2" Guid="{5bbca4a8-b209-48dc-a8c7-b23d3e5216fb}" EventSourceName="Microsoft-Windows-CAPI2" />
<EventID Qualifiers="0">513</EventID>
<Version>0</Version>
<Level>2</Level>
<Task>0</Task>
<Opcode>0</Opcode>
<Keywords>0x8080000000000000</Keywords>
<TimeCreated SystemTime="2016-07-14T01:01:06.745785900Z" />
<EventRecordID>20127</EventRecordID>
<Correlation />
<Execution ProcessID="1480" ThreadID="2472" />
<Channel>Application</Channel>
<Computer>MATTS-PC</Computer>
<Security />
</System>
<EventData>
<Data>

Details:
AddLegacyDriverFiles: Unable to back up image of binary Microsoft Link-Layer Discovery Protocol.

System Error:
Access is denied.
</Data>
</EventData>
</Event>

 

[kemical]

What will happen if I re-enable it?

You may possibly get the old error message back.

Personally I'd leave it be especially if it's working fine.

 

[BIGBEARJEDI]

Another precaution I'd suggest, is that if you are running drivers or apps that require W10 to disable beta-level drivers or libraries from running is that you "step-up" the level of your antivirus, antispyware, internet security, and firewall settings to maximum. I'd also consider doing all browsing to first time "unknown or previously never visited websites" using a separate secure browser mode such as the Avast Sandbox. There are security holes in some beta-drivers that hackers can exploit if you change that setting to bypass Microsoft approved (WHQL) drivers. Bypassing that process means that Microsoft never tested the driver with your OS and cannot guarantee it's security from threats. Personally, I never use this global setting lightly. I'd rather reinstall W10 ten times if I have to in order to avoid running my computer that way when exposed on the Internet.

<<<BIGBEARJEDI>>>

 

[kemical]

Personally I've never heard of a case where a user got a virus from running a beta driver but running decent AV is always a must.

 

[BIGBEARJEDI]

Yeah, I know weird. But that happened mostly in corporate network environments. In fact I recall a quite nasty virus that got into our network at WD when we were experimenting with W98 back in 1997 while W98 was in Beta and we were beginning deployment testing of workstations. We had connected some new software from one of our vendors that hadn't passed WHQL testing and we disabled the driver signing switch on a few of our W98 client workstations in Malaysia at one of our plants there. The virus got into their LAN and from their propagated through the WAN to US and then Europe. It was quite a mess! This was repeated at other customer sites over the years; so that's probably why I have such an aversion to it. My network there had 5,000 computers and I had about a 30% infection rate! It took us weeks to clean everything out.
BBJ

 

[Sankalp]

So yesterday i shut down my computer, and today when i started it up (about 2 hours ago) i can see the startup Motherboard message and all the BIOS stuff, but after that it is just a blank black screen, can't see the blue Windows logo, or that spinning circle indicating that it's loading. I don't even see my mouse cursor.

Now i would try it in safe mode but for reasons unknown you can't get to Windows 10 safe mode without getting first to the desktop, which i obviously can't right now.

I would try the repair installation tool, but after i boot from USB device with the install media, then i get the Windows logo and the loading circle, but after that it just ends up in a screen that says "Your PC ran into a problem we will restart it now" and with a small white text it reads error 0xC000021A.

(It doesn't say the 0% complete thing but other than that its all the same)

So any ideas guys? Was there some update that messed it all up? I didn't see any message saying installing updates or anything like that when i shut the PC down. Could it be that it installed something in the background or is my PC bust?

Hello. Make a recovery usb/dvd of your windows and boot from it. From there select "Repair my computer" and go to cmd.
Type:
bootrec.exe
bootrec /rebuildBcd
bootrec /fixBoot
bootrec /fixMbr

 

[Nitemuse]

For me nothing has worked I cant get into anything after i turn computer in it goes from blur screen press esc to black screen press esc to windows black screen with rotating beads to blue screen error 0XC000021A, I change boot choice i made a media intallation usb but it wont take n i cant reach the safe mode. I tried to back up files into external drive and even though it reads it and shows it as an option the Next button isnt highlighted so i cant even do that. Any ideas, please