FltMgr.sys file error typically occurs whenever Windows fails to process or read files that are kept on hard drivers, due to the fact that your system's FltMgr is either damaged or corrupted.
More similar errors:
cnmnsut.exe LPMLCHK.exe SystrayApp.exe
wsctool.exe rdvchg.exe epowertray.exe
What Is FltMgr.sys
The main function of the file is to assist the operating system in ensuring that data written on the hard drive is not corrupted and correct. When the file becomes problematic it only means that Windows cannot properly recognize it and it cannot process the file. The error you're seeing is basically caused by your PC being unable to read the files it needs to run properly. Every time Windows runs, it has to load up a series of "system" files which are designed to allow your computer perform a number of common functions. Although most Windows PCs are able to read their system files correctly, it's often the case that the likes of fltmgr.sys will either become corrupted or damaged - preventing your computer from being able to read the file and leading to the error you're seeing as a result.
How To Fix FltMgr.sys Errors
First restart your computer. This will ensure that issues related to the improper loading of File System Manager -- causing the error to surface -- will be rectified. It's possible that the file failed to load because of some errors, but more likely, this happens whenever a new update is loaded into your system. Restarting your computer will clear your system's RAM, allowing it to load again cleanly. If after doing this, should the error still persist, you need to check if your hard drives and hardware are functioning incorrectly. If they are not running properly its probably down to two things. The first is that your PC's hard drives are not properly connected to your system and two, Filesystem Filter Manager cannot read some hard drives correctly because of all system paths, only C drive is connected correctly. Any of these situations can cause your computer to produce a fltmgr.sys error message.
The next step to fixing this error is to then use a 'registry cleaner' program to repair any of the problems or issues that Windows may have had inside the registry database. This is a central directory of files which your computer will use to help it load up correctly, and is a vital part of every Windows system. Unfortunately, the registry may be causing a large number of problems for your PC - leading to the issues you're seeing on your screen. If you want to resolve this problem, it's recommended that you use a registry cleaner to scan through your computer and fix fltmgr.sys errors which are inside, which should allow it to run as smoothly as possible again.