IIS 7 - Troubleshooting

Re: Intermittent HTTP 500.19 error

steve schofield — Thu, 02 Jul 2009 23:15:44 GMT

Thanks for posting the solution and / or workaround. I'll add this to my tag of UNC connections.

http://weblogs.asp.net/steveschofield/archive/tags/UNC/default.aspx

Re: Intermittent HTTP 500.19 error

brian44 — Thu, 02 Jul 2009 11:04:24 GMT

Many thanks to both Anil and Steve. The root cause for the prevailing intermittent HTTP 500 error did appear to be that the MaxCmds registry setting is by default too low. To alleviate the issue, I created the MaxCmds dword, gave it a higher value, rebooted the web server and set the max mux configuration setting in samba to the same setting.

Re: Intermittent HTTP 500.19 error

steve schofield — Sun, 28 Jun 2009 02:20:41 GMT

Yes - It's applicable to IIS 7.

http://technet.microsoft.com/en-us/library/dd296694(WS.10).aspx

Dealing with a non-Windows OS as a UNC content is almost always more interesting than a windows backend when it comes to tuning. This article is a good starter.

Re: Intermittent HTTP 500.19 error

brian44 — Sat, 27 Jun 2009 10:31:11 GMT

Thanks Anil for your help, however I am still confused on a couple of points:

a) Is the HKLM\System\CurrentControlSet\Services\LanmanWorkstation\Parameters\ MaxCmds registry key valid for Windows server 2008? Does it require a reboot of the computer?

b) samba default configuration is by default very high and set to the maximum allowable limits by the OS. The broken SMB packets seem to be originating from the web server. Is it possible that we are hitting the maximum limit for supported web sites?

Re: Intermittent HTTP 500.19 error

anilr — Fri, 26 Jun 2009 16:45:30 GMT

http://technet.microsoft.com/en-us/library/dd296694(WS.10).aspx talks about how to tune the various smb parameters to match your load - of course the unc server side of the instructions will not apply since you are not using a windows server for that, but you would probably need to find similar instructions for samba.

Intermittent HTTP 500.19 error

brian44 — Fri, 26 Jun 2009 16:26:57 GMT

Hi,

We are currently running a Windows web server with approximately 250 sites and are recieving an intermittent 500.19 error, which affects a random selection of sites, and it affects ASP, ASP.NET and sites with naked HTML.

We see the following error when we view an effected site (apologies for munging):

Server Error ============ Internet Information Services 7.0 Error Summary HTTP Error 500.19 - Internal Server Error ----------------------------------------- The requested page cannot be accessed because the related configuration data for the page is invalid. Detailed Error Information Module IIS Web Core Notification BeginRequest Handler Not yet determined Error Code 0x80070038 Config Error Cannot read configuration file Config File \\?\UNC\10.0.3.25\home\domain.co.uk\public_html\web.config Requested URL http://domain.co.uk:80/ Physical Path \\10.0.3.25\home\domain.co.uk\public_html Logon Method Not yet determined Logon User Not yet determined Config Source -1: 0: Links and More Information This error occurs when there is a problem reading the configuration file for the Web server or Web application. In some cases, the event logs may contain more information about what caused this error. [1]View more information » 1. http://go.microsoft.com/fwlink/?LinkID=62293&IIS70Error=500,19,0x80070038,6001

This is often accompanied in the event log with an event with the message :

Could not load all ISAPI filters for site 'DOMAIN.CO.UK'. Therefore site startup aborted

I've previously seen a similar error reported at the link below, but this does not seem to help us as changing the MaxCmds registry entry seemingly has no effect.
http://forums.iis.net/t/1157405.aspx

The web server is Windows Server 2008 and the UNC share is a RHEL box with samba, site authentication is set to a specific domain user, asp impersonation is enabled, and all sites have individual application pools with their identity configured to the specific domain user.

When we run Network Monitor, we seem to find packets indicating that Windows has failed to send packets it's requested a response from for an affected site, however the network is running at 30-50% of available bandwidth and very occasional TCP sacks seem to be unrelated to this problem.

I would appreciate if any one could point me in the right direction.