This error message can be seen on both Windows 10 and 11, but only in case someone is repeatedly entering an incorrect PIN. This error message does not show up when entering an incorrect password. That said, there are reports that users often encounter this error message even though the computer has just started up, or they haven’t even touched the keyboard yet and the “A1B2C3” error message is there. In certain cases, someone has been trying to access their PC behind their backs and now the error message won’t go away. If you are reading this post, then it is likely that you or someone around is experiencing the same problem. Here, you’ll find quick workarounds and fixes to mitigate the issue and successfully log into your PC.
Purpose of the A1B2C3 Log-In Challenge Phrase
Before we begin, we would like to inform you that this error prompt is not an “error,” per see, but more like an attack prevention mechanism set in place by Microsoft.
Purpose of the A1B2C3 Log-In Challenge Phrase Bypass/Fix Continuous A1B2C3 Challenge Phrase Enter the A1B2C3 Challnge Phrase Use other Sign-In Options Create New Login PIN Reset the Access Control List Change Owner of NGC Directory Reset ACL Remove Ngc Folder Content and Create Fresh Files Closing Thoughts
In the modern world, Brute force attacks are becoming more and more common. A Brute force attack is when repeated attempts are made to penetrate the system/network. In case someone is trying to log into your user account remotely, they will be asked to enter this challenge phrase to restrict their access to the Lock Screen, where they can continue guessing your password. That said, the error message should only show up once. Once you have entered the challenge phrase, you should be brought back to the Lock Screen where you can enter your PIN/biometric information/password, and continue to log into your account. However, according to online forums, that is not always the case. Users are often stuck inside the same loop or are asked to enter the “A1B2C3” challenge phrase every time they want to log in. Let us now continue to see how we can bypass or mitigate the problem once and for all.
Bypass/Fix Continuous A1B2C3 Challenge Phrase
There are methods to both bypass the A1B2C3 challenge phrase in case it was a one-time prompt, or fix the issue if you are encountering the prompt continuously and repeatedly. We suggest that you perform the given solutions below in the given chronological order that go from simply bypassing the challenge phrase to resolving the repeated prompt. Additionally, perform all the methods using an administrator account. Note that the methods to fix the continuous asking of the challenge phrase need to be performed while you are logged in. Therefore, you might need to perform either one of the first two solutions nonetheless.
Enter the A1B2C3 Challnge Phrase
The first and least-extensive workaround is to simply do what the computer is asking. By entering the challenge phrase, you will be taken back to the Windows lock screen, where you must carefully enter the correct credentials to log in.
Use other Sign-In Options
Alternatively to the method above, you can also use other sign-in options to log into your account. If you have configured other methods to sign in, such as a password, then you can use that to sign in instead. Carefully enter the correct credentials to log into your computer account. You should now be logged into your account. Hopefully, you won’t be asked to re-enter the A1B2C3 challenge phrase unless the wrong credentials are entered again. However, if the issue persists, then we suggest that you continue to perform the mitigation methods shared below.
Create New Login PIN
In case there is any issue with the information stored on the computer regarding your PIN, you ought to try deleting the old PIN and creating a new one. This way, the locally-stored data will be reset and new files will be created. Here are the steps to create a new PIN in Windows: Once a new PIN has been configured, lock/sign out of your account and check whether you still encounter the “A1B2C3” challenge phrase. The existing PIN will now be removed. If you do, then we might need to dig a little deeper to resolve the issue.
Reset the Access Control List
Windows OS stores an Access Control List (ACL) to authenticate which passwords and PINs should allow an individual to log in. This is stored inside the “Ngc” folder located at the following path: An issue with the ACL can prompt the challenge phrase to pop up over and over again. Therefore, it must be reset. However, before you can reset it, you must gain full control over the NGC folder so you do not encounter the “Access is denied” error.
Change Owner of NGC Directory
Now that you have the required permissions (since you are logged in from an administrative account), continue to perform the steps in the next section to reset the ACL. Note: You may not be able to enter the path directly into the navigation bar in File Explorer due to a lack of permissions. Additionally, since the “AppData” directory in the given path is hidden, you can access it by manually entering the directory into the navigation bar (for the said folder only), or accessing it by viewing hidden items.
Reset ACL
Follow these steps to reset the ACL and check whether it resolves the issue: Now check whether the “A1B2C3” prompt has gone away. If it hasn’t, then there is still one more trick up our sleeve.
Remove Ngc Folder Content and Create Fresh Files
This is the most extensive mitigation method of the A1B2C3 challenge phrase and should only be used in case none of the methods above have worked. Since the “Ngc” folder stores your login information, you must delete it and then recreate a new PIN. Here is how: Note: You can either delete the data inside the Ngc folder or simply rename it. Moreover, we also recommend that you create a system restore point before proceeding so that you can revert your settings in case things do not go as planned. Now check whether you continuously see the “A1B2C3” challenge phrase when attempting to log in. Alternatively, you can simply rename the Ng folder to “Ngc.old”. As reported, this last solution works for most users and resolves the issue. However, we only need to be extreme with the Windows OS when absolutely necessary.
Closing Thoughts
We repeat that the “A1B2C3” challenge phrase is not an error, but a prevention mechanism of Windows to secure your account and protect your data from Brute force attacks. However, when Windows repeatedly asks you to enter the challenge phrase, it means that something might be wrong. The solutions given in this post should surely work and fix the issue. Let us know which solution worked for you in the comments below, so our readers can get a better understanding of how aggressive their approach should be to fix it from the very beginning.
