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nealcaxiell's avatar
nealcaxiell
Copper Contributor
Oct 16, 2023

IIS App pool crashes

Hi,

 

We are experiencing some random app pool crashes on one of our production servers. I've put in place additional logging and analysed it through DebugDiag. The output from that is:

 

In w3wp.exe.11696.dmp the assembly instruction at clr!Assembly::GetSecurityDescriptor+1a in C:\Windows\Microsoft.NET\Framework\v4.0.30319\clr.dll from Microsoft Corporation has caused an access violation exception (0xC0000005) when trying to read from memory location 0x00000040 on thread 9

 

I need further help to troubleshoot this and this seemed like the best place, but if it's not I'd appreciate someone pointing me in the right direction. Happy to post the full report if that would help or any other information that would be of use. Thanks.

2 Replies

  • Harold-Picado's avatar
    Harold-Picado
    Brass Contributor
    Jul 14, 2026

    Hi,

    The crash is occurring inside clr.dll, but that does not necessarily indicate a CLR defect. An Access Violation (0xC0000005) is commonly caused by memory corruption introduced by native code loaded into the IIS worker process.

    The first step is to identify all third-party native modules loaded into w3wp.exe and review the DebugDiag call stack and loaded module list for non-Microsoft components. I would also recommend checking the Windows Application Event Log for Event ID 1000 or 1026 around the crash time, as the faulting module may provide additional clues.