How to Fix “LogonUI.exe – Application Error” in Windows 10

Yesterday, when I tried to shutdown my Windows 10 PC after spending two hours watching some videos on Youtube, it showed an error – “Windows sign-in: LogonUI.exe – Application Error”. The error description said something about the memory addresses and unable to write the data there – “The instruction at 0x63D00F43 referenced memory at 0x06584000. The required data was not placed into memory because of an I/O error status of 0xc000009c.” This error could emanate from a myriad of sources – the failure of the hard disk, the problems with the RAM modules, the faulty data cables, the power supply unit not able to supply proper voltage or current to the hard disks, corruption of the user profile, corruption of system files and more.

Apart from checking all the hardware and cleaning up all the dust that accumulates inside the computers, you can follow these simple steps to resolve this problem:

Windows LogonUI.exe Error

1. Run the disk check tool to fix the file system
Perhaps due to power failure or cheap quality cables, your hard disk could stop working in the middle resulting in the corruption of the file system itself. You can fix it easily by running the disk check tool on the system drive (the partition where Windows is installed, usually C:). If you are able to boot into Windows, then just right-click on the disk drive, choose Properties, then Tools and then click on the Check button. It will inform you that the process will be done at next boot at which point you should reboot your system. If you are not able to boot into Windows normally, then use the Windows DVD to boot into the repair mode, then open the command prompt and give this command : chkdsk /F C: where C: is your system drive.

Windows LogonUI.exe Error

2. Replace possible corrupt files with healthy ones
After checking your file system, you should restore all the healthy files from Windows DVD so that the corrupt system files (if any) can be replaced with their original healthy images. To do this, open an Administrator command prompt (press Win+X and then choose Command Prompt (Admin) and then give the following command : Dism /Online /Cleanup-Image /RestoreHealth /Source:wim:D:/sources/install.wim:1 /limitaccess. Here the Windows DVD is loaded on the D: drive, so if your DVD drive is something else, change accordingly.

Windows LogonUI.exe Error

3. Create a new user account
If despite the first two steps, your system is showing the same error during the shutdown or startup, then perhaps your user profile has become corrupt. There is no way to fix a corrupt user profile other than by replacing it with a new user profile. In order to do so, just create a new user account in Windows and start using this new user account instead of the older user account. You can always backup your files from your older profile and use them in the new profile.

Conclusion: The LogonUI.exe application error could mean many things – hardware problems, malware infection or the system files corruptions. You can take a few steps to fix this problem by restoring healthy Windows system files from the installation media.