What is CompatTelRunner.exe?

The genuine CompatTelRunner.exe file is a software component of Microsoft Windows by Microsoft Corporation.
"Compattelrunner.exe" is the Microsoft Compatibility Appraiser, an executable file installed in Windows 7 and 8.1 machines by the update described in KB2977759. It is installed in "C:\Windows\System32". It is set to execute by the Task Scheduler which can be used to disable it. Large numbers of instances may operate concurrently. It scans application files residing on the computer to assess their compatibility with Windows 10 if an upgrade is performed. Described as part of the Customer Experience Improvement Program for PC's which opt-in, it collects and sends telemetry to Microsoft servers. Although not a heavy CPU user, it can monopolize disk I/O for up to 20 minutes at startup. Microsoft Corporation was founded by Paul Allen and Bill Gates in April 1975 and is now the world's largest software producer by revenue, with an emphasis on Cloud software services for the future.

CompatTelRunner stands for Compatibility Appraiser Telemetry Runner

The .exe extension on a filename indicates an executable file. Executable files may, in some cases, harm your computer. Therefore, please read below to decide for yourself whether the CompatTelRunner.exe on your computer is a Trojan that you should remove, or whether it is a file belonging to the Windows operating system or to a trusted application.

Click to Run a Free Scan for CompatTelRunner.exe related errors

CompatTelRunner.exe file information

Windows Task Manager with CompatTelRunner
CompatTelRunner.exe process in Windows Task Manager

The process known as Microsoft Compatibility Telemetry belongs to software Microsoft Windows Operating System by Microsoft (

Description: CompatTelRunner.exe is an important part of Windows, but often causes problems. The file CompatTelRunner.exe is located in the C:\Windows\System32 folder. Known file sizes on Windows 10/8/7/XP are 67,816 bytes (25% of all occurrences), 37,096 bytes and 13 more variants. 
The CompatTelRunner.exe file is a Windows system file. The program is not visible. It is digitally signed. It is a Microsoft signed file. Therefore the technical security rating is 0% dangerous, however you should also read the user reviews.

Uninstalling this variant: In the event of any problems with CompatTelRunner.exe, you can do the following:

Recommended: Identify CompatTelRunner.exe related errors

Important: Some malware disguises itself as CompatTelRunner.exe, particularly when not located in the C:\Windows\System32 folder. Therefore, you should check the CompatTelRunner.exe process on your PC to see if it is a threat. We recommend Security Task Manager for verifying your computer's security. This was one of the Top Download Picks of The Washington Post and PC World.


User Comments

Necessary for Windows 10 (installed with kb2977759): "This update performs diagnostics on the Windows systems that participate in the Windows Customer Experience Improvement Program. These diagnostics help determine whether compatibility issues may be encountered when the latest Windows operating system is installed. This update will help Microsoft and its partners ensure compatibility for customers who want to install the latest Windows operating system."
  No_W10   (further information)
Uses tons of CPU and IO on occasion, however, is made by Microsoft and comes with windows.
If a file is signed from microsoft NEVER delete it, Doing so may cause system instability and possibly break windows. I have never had any issues with this process and so have no reason to delete. The only way this process could be bad is if you have obtained a Rootkit which is unlikely.
It does a lot of disk activity on my Win7-64, as it analyses hundreds of files per minute. Might be part of some scheduling task. I also know that advice is hilarious, as you can read above: "uninstall the software Microsoft Windows"
  Pedro Lucas  
it has a really high disk rate usage of 10 - 20% in the task manager.
It's garbage. Windows is forcing telemetry onto users now. It's nothing but telemetry crap. Take ownership, change permission to full, delete the file.
  Sick of MS's Hijacking Crap  
Seems important but causes sky-high CPU and Disk usage.
My installation folder for Rocket League was locked, I could not change the permissions. Using Lockhunter I established that Compattelrunner was preventing access. Once I terminated it access was regained.
Well.. it is invisible as being installed viewing installed programs in control panel. That makes it suspicious if not dangerous.
  Ronald Duck  
Legit program from Microsoft for Windows. However, it caused constant high disk usage, significantly crippling my laptop. Disabling it in the task scheduler rather than deleting it solved the problem and there seems to be no repercussions.
Spyware from Microsoft. Will continue to run despite shutting it off in the computer settings. While not dangerous, it's a nuisance, and should be removed.
86,368 bytes here. Huge disk I/O when running. Has Microsoft Digital Signature. Unsure action of file so leaving it alone, but may terminate in Taskmgr.exe. Without deleting, one could also restrict access or move the file, though I think that would require trusted installer access rather than adminstrative.
  John V  
Appears to be Microsoft collecting info for themselves. Locks even fast machines at 100% disk use for hours.
I can't tell you exactly what it does, but often times my computer will grind to a halt, I go into task manager, and low and behold it's this same process eating 100% of my disc space for some reason. I just disabled it and it doesn't seem to cause any problems (infact it fixes them), but I'm hesitant to delete it since it IS a microsoft process.
My virus scanning program is often reporting CompaTelRunner as crashed. Is is one of the causes that eventually will lead to my leaving Windows all together
  Nils Lundborg  
This program is complete resource PIG!!! After resuming my Windows 7 (SP1 and all Microsoft updates installed) computer from sleep or starting up my system fresh each morning, this program ran for 20-40 minutes and used nearly 100% of my disk I/O (Input/Output)!!! After spending weeks isolating this problem and determining what function this application performed, the first thing I did was check whether I was 'opted-in to the Microsoft Customer Experience Improvement Program'. Went to Control Panel In the search box typed 'privacy' Click on 'Change Customer Experience Improvement Program settings' Setting was set to 'No, I don't want to participate in the program.' Now knowing the name of the program 'CompatTelRunner.exe', I looked through the Windows Task Scheduler and found a couple entries under: Task Scheduler Libray: Microsoft: Windows: Application Experience: It's set to run not once, but twice every day! Once at 3:00am with no conditions (e.g., only when system is idle) and again at 11:30pm. In addition to that, the program is set to 'Run task as soon as possible after a scheduled start is missed.'. Well that explains why it started running every morning when I resumed my system from standby or started it up fresh after a shutdown! This stupid program scans every executable and every .dll file on your entire system and that's why it takes 40+ minutes to complete! I hope this information helps some other poor soul that is experiencing this problem. I also renamed the program in C:\Windows\System32 just in case some Windows update re-enables the task in the Task Scheduler.
    (further information)
It takes a hell lot of disk, but i don't know if it's essential.
It is not only a violation of basic human right of privacy... It actually prevents one from being productive (the very core of why people use windows product) by starting to spin the disk exactly when you need the computer to be responsive...
Another poorly written microsoft module that takes huge amount of CPU power, disk usage is almost at MAX when it works
Windows Telemetry and spy program.
  Nick H  
Microsoft spyware/telemetry. Time to move to Linux
  Ima Tester  
SOLUTION: It's part of the "Windows Customer Experience program" and collect data & send it to Microsoft. To stop it, start the Task Schedule Library (Start - Run - taskschd.msc). There you find it in the Task Schedule: Location: \Microsoft\Windows\Application Experience Name: Microsoft Compatibility Appraiser Right click on “Microsoft Compatibility Appraiser” and select “Disable” You can also disable the tasks "AITAgent" and "ProgramDataUpdater" in the same folder. To stop Windows to send data to Microsoft, you can disable under Microsoft/Windows/Customer Experience Improvement Program the tasks Consolidator, KernelCEIPTask, and UsbCEIP. Source:
  Leon   (further information)
bremst Windows 8.1 aus
I use expensive Windows Server 2016 OS and disabled ALL telemetry options. I switched from Windows 10 Pro to get rid of telemetry. Despite of that, the telemetry just turns on... My HDD light is flashing like a small star, my PC is slower than a turtle, my opened windows are unable to redraw, my screen flickers, I am unable to open Task Manager using CTRL+ALT+DEL (it is unable to draw it's window). The only solution was to turn off the computer or to log out. I had to start again all tasks (some of them has been processing for days & I have lost the results). There are NO info why it starts. There are NO info how to completely remove it (I am sick when I click "turn-it-off" and MS turns things on after a restart). I am thinkng about writing a tiny DoNothing.exe program and putting it instead of CompatTelRunner. And yes, this nasty thing comes with Windows. It is a legit reason why people call Win10 a spyware. You can do it with WS2016 too.
It uses my data bandwidth.
-high cpu usage -scans your system -sends data 100% spyware
  g. uest  
It a monitor process. It's not harmful, but it isn't helpful or necessary. If it is causing issues, remove it, if it isn't, don't worry about it. It does seem to toss back false-positives in some AV programs.
  Dr. Sudoku  
Moved it to it's parent folder because of excessive disk usage. I used linux to move the file from system32 to windows effectively disabling it.
Anything which send information without my permission to anyone is SPYING.
  Henry Martin  
These diagnostics help determine whether compatibility issues may be encountered when the latest Windows operating system is installed.
  JamaL   (further information)
Windows does regular updates of any OS and any Service Pack. In order to do this, it requires a process called CompatTelRunner.exe.
  Steven   (further information)
I never willingly accepted to supply Windows with telemetry information. But Windows sneakly installed with an update. It is not in installed programs and it is invisible when running. If it wasn't for crippling my pc I would had never found it. For me this is spyware from Windows as I do not want to supply telemetry information.

Rating chart

Summary: Average user rating of CompatTelRunner.exe: based on 60 votes with 33 user comments. 8 users think CompatTelRunner.exe is essential for Windows or an installed application. 6 users think it's probably harmless. 18 users think it's neither essential nor dangerous. 8 users suspect danger. 20 users think CompatTelRunner.exe is dangerous and recommend removing it. 9 users don't grade CompatTelRunner.exe ("not sure about it").

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Best practices for resolving CompatTelRunner issues

A clean and tidy computer is the key requirement for avoiding problems with CompatTelRunner. This means running a scan for malware, cleaning your hard drive using 1cleanmgr and 2sfc /scannow, 3uninstalling programs that you no longer need, checking for Autostart programs (using 4msconfig) and enabling Windows' 5Automatic Update. Always remember to perform periodic backups, or at least to set restore points.

Should you experience an actual problem, try to recall the last thing you did, or the last thing you installed before the problem appeared for the first time. Use the 6resmon command to identify the processes that are causing your problem. Even for serious problems, rather than reinstalling Windows, you are better off repairing of your installation or, for Windows 8 and later versions, executing the 7DISM.exe /Online /Cleanup-image /Restorehealth command. This allows you to repair the operating system without losing data.

To help you analyze the CompatTelRunner.exe process on your computer, the following programs have proven to be helpful: ASecurity Task Manager displays all running Windows tasks, including embedded hidden processes, such as keyboard and browser monitoring or Autostart entries. A unique security risk rating indicates the likelihood of the process being potential spyware, malware or a Trojan. BMalwarebytes Anti-Malware detects and removes sleeping spyware, adware, Trojans, keyloggers, malware and trackers from your hard drive.

Other processes

CompatTelRunner.exe [all]