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Anomaly : Meaningless REX Prefix Used RRS feed

  • Question

  • I am getting one caution some message " Anomly : Meaningless REX Prefix used " when ever I performed any command based operations like gpupdate and others even it is being displayed when ever I opened command prompt.

    I didn't find any error logs in event viewer and I googled for it but I didn't get any solution.

    I am a member of Domain admins group and other person in the same group getting the same message.

    We couldn't able to find out the solution. so please help me out in this regard.

    Our Environment :

    Windows AD 2012 , I am using Windows 7 sp1 x64 and and using Active Directory Admin tools.


    getting the same message while performing gpupdate.


    Please let me know if any additional information is required.

    Thursday, March 10, 2016 11:26 AM

Answers

  • Please check the screenshot here 

    http://answers.microsoft.com/en-us/windows/forum/windows_7-performance/anomaly-meaningless-rex-prefix-used/13efd2ab-6108-4454-94e0-d231801ec7bc?auth=1

    I looked at your screenshot, and my guess is that some non-Microsoft component (driver, software, utility) is installed and has "extended" the command processing environment with a REXX interpreter.

    A quick web search reveals that some people have found either AVG Antivirus software or NVidia display software might be the cause, and that uninstalling those could solve the issue.


    Don [doesn't work for MSFT, and they're probably glad about that ;]

    • Proposed as answer by Wendy Jiang Monday, March 21, 2016 9:45 AM
    • Marked as answer by Yan Li_ Friday, March 25, 2016 7:07 AM
    Wednesday, March 16, 2016 5:48 AM

All replies

  • > I am getting one caution some message " *Anomly : Meaningless REX Prefix
    > used *"
     
    Never heard before... Screenshot?
     
    Thursday, March 10, 2016 4:02 PM
  • Hi,
    Can I ask which application is used for running gpupdate command, cmd or other 3rd party tool? As Martin said, it is better to offer us the screenshot.
    According to my research, the error is a Java issue, it may be a good starting for your troubleshooting.
    Regards,
    Wendy

    Please remember to mark the replies as answers if they help and un-mark them if they provide no help. If you have feedback for TechNet Subscriber Support, contact tnmff@microsoft.com.

    Monday, March 14, 2016 9:05 AM
  • Hi Martin,

    I could n't able to paste the screenshots here it is asking for e-mail verification not yet done , but unfortunately I 've posted this on MS Community and here is the link .

    Please check the screenshot here 

    http://answers.microsoft.com/en-us/windows/forum/windows_7-performance/anomaly-meaningless-rex-prefix-used/13efd2ab-6108-4454-94e0-d231801ec7bc?auth=1

     

    Monday, March 14, 2016 11:49 AM
  • Hi Wedney,

    I'm not using any 3rd party tools for gpupdate I'm using cmd only. 

    This message is appearing whenever I open the cmd and the first line is that message only.

     

    Monday, March 14, 2016 11:51 AM
  • What do you find in HKEY_CURRENT_USER\Software\Microsoft\Command Processor ?
     
    Monday, March 14, 2016 1:57 PM
  • CompletionChar ( 9 )

    DefaultColor ( 0 ) 

    Enable Extensions ( 1 ) 

    PathCompletionChar ( 9 )

    Tuesday, March 15, 2016 6:57 AM
  • I'm not using any 3rd party tools for gpupdate I'm using cmd only. 

    This message is appearing whenever I open the cmd and the first line is that message only.

    Do you use AVG Anti-Virus ?

    https://support.avg.com/answers?id=906b0000000D4GzAAK


    Don [doesn't work for MSFT, and they're probably glad about that ;]

    Tuesday, March 15, 2016 7:39 AM
  • Hi DON,

    We are using Symantec Endpoint Protection only.

    Tuesday, March 15, 2016 7:48 AM
  • > CompletionChar ( 9 )
    > DefaultColor ( 0 )
    > Enable Extensions ( 1 )
    > PathCompletionChar ( 9 )
     
    That's ok. I'm out of the game.
     
    Tuesday, March 15, 2016 8:45 AM
  • Hi Martin,

    Why I couldn't able to upload images in this forum 


    Wednesday, March 16, 2016 5:36 AM
  • Hi Martin,

    Why I couldn't able to upload images in this forum 


    you need to be verified, you can request verification here

    https://social.technet.microsoft.com/Forums/en-US/910ceecf-e32a-41d3-9b6b-5a9a1ec6c59d/verify-your-account-33?forum=reportabug


    Don [doesn't work for MSFT, and they're probably glad about that ;]

    Wednesday, March 16, 2016 5:45 AM
  • Please check the screenshot here 

    http://answers.microsoft.com/en-us/windows/forum/windows_7-performance/anomaly-meaningless-rex-prefix-used/13efd2ab-6108-4454-94e0-d231801ec7bc?auth=1

    I looked at your screenshot, and my guess is that some non-Microsoft component (driver, software, utility) is installed and has "extended" the command processing environment with a REXX interpreter.

    A quick web search reveals that some people have found either AVG Antivirus software or NVidia display software might be the cause, and that uninstalling those could solve the issue.


    Don [doesn't work for MSFT, and they're probably glad about that ;]

    • Proposed as answer by Wendy Jiang Monday, March 21, 2016 9:45 AM
    • Marked as answer by Yan Li_ Friday, March 25, 2016 7:07 AM
    Wednesday, March 16, 2016 5:48 AM
  • > Why I couldn't able to upload images in this forum
     
    You didn't try hard enough... :-)))
     
    Wednesday, March 16, 2016 10:35 AM
  • I have to challenge this answer.  this has nothing to do with the programming language REXX. 

    I am currently getting the same error reported, displayed in my command line, (cmd, bash, powershell, any terminal environment on my windows machines).   

    If you execute a command with no terminal output (say cd somewhere) , it works fine. 

    If you execute a command with terminal output (say a dir or ls ) then you see the error : 

    "[0x7FFFAC425D10] ANOMALY: meaningless REX prefix used" 

    .. didsplayed anywhere from 3-12 times, and sometimes in bursts  of 1-2 times. this outpuit makes the command propmpt unusable, as all you see is this error. 

    Dpnt try to google this one. what you will find in the results is a few things :

    1. This issue is rare

    2. This issue is not directly tied to any specific piece of software. You will find however, that this issue  starts after the installation of some tool, or upon first use. (I myself do not have any of the software reported) 

    3. There is *some* speculation around video drivers, nut no solid evidence. 

    Machine information 

    1. Machine 1 - Custom build - ( dual Radeon 7000 cards)  Server 2016 Tech preview 5

    2. Machine 2 - HP Laptop ( nvidia onboard )  Windows 10 Pro 

    3. Machine 3 - Gateway / custom ( NVidia card ) Windows Server 2012 R2

    Repro 

    - clean machine (format the hard drive install window 10) 

    - install Git for windows (any of the last 7 versions )

    - reboot

    - Attempt to use bash command line,

    - After the error shows up once, it will show up in any terminal that you use. (power shell, cmd, or bash on windows) 

    I doubt this forum will solve an issue of this magnitude. I dont mean that in a bad way, just that this is going to take alot of research. The actual error is due to an assembly bug, who knows where that is. the applications I and others have installed, are most likely not causing the issue, but rather transitioning to a state, in some low level code ( perhaps a graphics driver ). 

    What can we do? 

    Anyone know how to fitler out cmd output? We could atleast write a script that would never show this error? 


    Rex Whitten

    Wednesday, September 28, 2016 6:33 PM
  • I have to challenge this answer.  this has nothing to do with the programming language REXX. 

    In hindsight, I agree with you. My original response was a complete guess, and looks to have been completely wrong.

    I just found this discussion at SO, and I think it likely to be much closer to the correlation:

    http://stackoverflow.com/questions/36873664/anomaly-meaningless-rex-prefix-used

    If I was competent with debugging (but I'm not), I'd start there. Still seems like it would be a difficult task, as it may require symbols for non-MSFT libraries (graphics driver libraries etc) ?

    If I was having this problem, I'd raise a support case with Microsoft to get them to debug it. Which still might not determine *why* it's doing what it's doing...

    Since you can repro, would removing the AMD/NVidia cards be an option (assuming that would remove the graphics driver libraries from the equation?)


    Don [doesn't work for MSFT, and they're probably glad about that ;]

    Wednesday, September 28, 2016 9:57 PM
  • I've Just started getting this problem today. 

    [0x7FFAE39A70E3] ANOMALY: use of REX.w is meaningless (default operand size is 64)

    So I'd be happy to know the cause :-)

    Tim

    Friday, September 30, 2016 7:58 AM
  • This seems to have multiple causes, and seems to be tied to vendor's improperly creating patches for Windows 10 "Anniversary Edition" (aka Redstone 1).  See here for another person who had the issue and found it was attributed to TrendMicro Antivirus (I'm seeing the same thing, and there is apparently a patch available from TrendMicro now):

    http://www.areresearch.net/2016/10/trend-micro-officescan-anomaly-use-of.html

    Check for updates for all of your software, particularly Antivirus software, and/or any which updated itself recently. 

    Monday, October 24, 2016 3:47 PM