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Unable to acquire .NET debugger interface. Error: 8027025b


I migrated from 8.1 computer to a new one with Win 10. Although I made the same steps (or at least I hope so) as on my old computer, I'm not able to run !windex because of the error..

I copied assemblies to "c:\Program Files (x86)\Windows Kits\10\Debuggers\x64" (and x86) folder from the zip file.

An output from start looks like this:
0:000> .load netext
netext version Jan 21 2016
License and usage can be seen here: !whelp license
Check Latest version: !wupdate
For help, type !whelp (or in WinDBG run: '.browse !whelp')
Questions and Feedback: 
Copyright (c) 2014-2015 Rodney Viana ( 
Type: !windex -tree or ~*e!wstack to get started

0:000> !windex
Unable to acquire .NET debugger interface. Error: 8027025b
c0000005 Exception in netext.windex debugger extension.
      PC: 00007ffa`8434967b  VA: 00000000`00000000  R/W: 0  Parameter: 00000000`00000000
0:000> !wver
Unable to acquire .NET debugger interface. Error: 8027025b

What might be wrong?


stejcz wrote Nov 28, 2016 at 11:19 AM

I don't see exceptions after !windex and !wver. So what probably helped:
I have to copy symbols cache from old computer to c:\symbols (or any other local directory).
And then not to use just ".symfix", but ".symfix c:\symbols" which fixed symbol search path so that it added the symbol cache.

More info here:

Was that the problem?
Some pdbs for ntdll can't be downloaded during several past dasy (maybe weeks?).. :(

rviana wrote Nov 28, 2016 at 7:03 PM

This error: "Unable to acquire .NET debugger interface. Error: 8027025b" happens for one these 3 reasons:
  1. Process is not .NET
  2. Dump is corrupted
  3. The symbols for the particular version of .NET is missing in the symbol server or there is no symbol server configured
To verify if the problem is with DAC (.NET Debugger Interface), run this command in WinDBG which will go through the same APIs NetExt does:
.cordll -u -ve -l

stejcz wrote Dec 6, 2016 at 10:50 AM

Yes, I think the (3) was my case. Thank you for your response.
Now it's working ok.