SAPConsole can't initialize unexpected exception

Question

I have an intermittent problem with SAPConsole and IIS.  Sometimes I can connect fine and other times I get the error u201CError: Canu2019t initializeu201D (version 7.1 patch level 4) or u201CError: Unexpected exceptionu201D (version 6.4 patch 20).
I have installed the two different versions of SAPConsole on two separate servers, both running Windows Server 2003.  I first installed 6.4 and tried it with telnet first as I had not installed IIS on this server.  SAPCNSL.EXE and Telnet worked well in testing.
I then installed 7.1 on another server where I already had IIS installed.  This instance of IIS already had some internal web sites configured, so I followed the installation instructions and added a virtual directory, etc.  I connected to the URL per the instructions and it worked.  I thought, u201CWow, this is easy.u201D  I connected several times both from a Motorola gun with Windows CE and also from my own PC.  However, late that afternoon I started getting u201CError: Canu2019t initializeu201D.  I stopped and started the web page, the application pool, IIS services, and finally rebooted the server, none of which fixed the problem.  Then, after leaving it alone for about 30 minutes, I tried it once more and it worked (for a while).  Also, I could run SAPCNSL.EXE at any time and it would always work.  Unfortunately, the SAPTrace file only seems to record activity for SAPCNSL.EXE but not ISAPI_SAPCNSL.DLL.
After fighting that server for a day or two, I decided to install IIS on the original server where I had installed SAPConsole 6.4.  I hoped a fresh install of IIS with no previous configuration might help.  Again, it worked fine at first but soon started giving the error u201CError: Unexpected exceptionu201D intermittently, just like the other server.  However, on this version, the SAPTRACE file records activity for both the EXE and the DLL.  When I receive the error the trace file looks like this:
17:31:41: This is a trace file for SAPConsole patch 20.2
17:31:41: Fatal Error: Can`t find module "isapi_sapcnsl.dll" in process modules list
17:31:41: Fatal Error: Can`t load Central module "sapcnsl.dll"
17:31:41:      Error code: 126
17:31:41: InitApp success: id = 01B03888_15, connection = 00000000, displayer = 00000000, profile = 01B04B30
17:31:41: Error: unexpected exception
17:34:28: Start request for session
17:34:28: Start request for session
17:34:28: Fatal Error: Can`t find module "isapi_sapcnsl.dll" in process modules list
17:34:28: Fatal Error: Can`t load Central module "sapcnsl.dll"
17:34:28:      Error code: 126
17:34:28: InitApp success: id = 01B0C3C0_167511, connection = 00000000, displayer = 00000000, profile = 01BD0048
17:34:28: Error: unexpected exception
I have looked in both versions of the ISAPI_SAPCNSL.DDL files and can see that those different error messages are contained in the respective versions, so the error is coming from the DLLs, not IIS.  Also, since the EXE file can always connect, I do not believe the problem is from SAP.  I have defined various profiles, both by using the SAPLOGON.INI file and by defining the connection manually, to various SAP systems.  Once the server starts failing, it does not matter which profile I specify as the default or use as a parameter in the URL, I still get the error.  Also, the two servers do not necessarily fail at the same time.  That is, one server may start failing while the other continues to connect successfully.  The server that has failed will start working again after a varying period time (30 minutes to several hours).
So, from the trace file from the 6.4 version, what do the errors mean?  Specifically, u201CCan`t find module "isapi_sapcnsl.dll" in process modules listu201D, u201CCan`t load Central module "sapcnsl.dll"u201D and u201CError code: 126u201D?  I have placed entries in the PATH environment variable on both servers.
How can I get the trace file with 7.1 version to work?  I suspect I might see similar messages.  I read an OSS note about a correction for the trace file not working with the DLL in an early version of the 6.4 version, but was that correction not carried over to the 71 version?
I have tried various configuration changes to IIS, such as selection the options for memory recycling in the application pool.  I will make a change and it will seem to have worked and then later it will fail again.
Does any one have any ideas?

Answer 1

Apparently resolved intermittent problem with SAPConsole.  Changed IIS configuration on to have no worker process recycling or shutdown of idle worker processes or pinging of worker processes.  This was a problem since the guns go to sleep and are then not connected to the network.  There is still a connection timeout which I have set to one hour.  Also I unselected the enable session state option of the virtual web page which means there is no session timeout.  Later found OSS note (1221578) under IIS (not SAPConsole) that recommended the same things but until I knew it was an IIS issue I would not have searched for IIS.