IIS webagent crashes / What should we check to prevent those in the IIS configuration ?

Document ID : KB000041315
Last Modified Date : 14/02/2018
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Issue:

Randomly the IIS server is crashing. Checking the dump, the issue is related to the Webagent.

Environment:

Webagent 12.52CR01 on windows 2012 64 bit / IIS 8.0

Cause:

Checking the dump we can see that there is a problem with the DDL loaded by the Webagent :
-> both ISAPI6WebAgent.dll and IIS7WebAgent.dll are loaded at the same time

Resolution:

Checking the web.config for the different website. Need to make sure that you have the following:

<isapiFilters>
webagent\win64\binISAPI6WebAgent.dll" preCondition="classicMode,bitness64"
webagent\win32\binISAPI6WebAgent.dll" preCondition="classicMode,bitness32"
</isapiFilters>

<modules>
<add name="CASiteMinderWebagentModule" preCondition="integratedMode,bitness64" />
<add name="CASiteMinderWebagentModule-32" preCondition="integratedMode,bitness32" />
</modules>

-> If you are missing a preCondition it may crash the IIS server.