Load System.Web fails but load System.Xml succeeds

Question

From the fusion logs, the problem is System.Web 2.0 is redirected to System.Web 4.0 which is NOT in the GAC and therefore fails to load. I compared it to System.Xml 2.0 which also gets redirected to System.Xml 4.0 but that is indeed in the GAC and therefore loads successfully.

Our app.config is forcing the redirect from 2.0 assemblies to 4.0 assemblies.

Here’s a snippet from the failing System.Web bind:

LOG: This bind starts in default load context.
LOG: Using application configuration file: C:\Windows\SysWOW64\pnbrksvc.exe.Config
LOG: Using host configuration file: 
LOG: Using machine configuration file from C:\Windows\Microsoft.NET\Framework\v4.0.30319\config\machine.config.
LOG: Version redirect found in framework config: 2.0.0.0 redirected to 4.0.0.0.
LOG: Post-policy reference: System.Web, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a
LOG: GAC Lookup was unsuccessful.

Here’s a snippet from the successful System.Xml bind:

LOG: This bind starts in default load context.
LOG: Using application configuration file: C:\Windows\SysWOW64\pnbrksvc.exe.Config
LOG: Using host configuration file: 
LOG: Using machine configuration file from C:\Windows\Microsoft.NET\Framework\v4.0.30319\config\machine.config.
LOG: Version redirect found in framework config: 2.0.0.0 redirected to 4.0.0.0.
LOG: Post-policy reference: System.Xml, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089
LOG: Binding succeeds. Returns assembly from C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Xml\v4.0_4.0.0.0__b77a5c561934e089\System.Xml.dll.
LOG: Assembly is loaded in default load context.

I would assume .NET 4 comes with System.Web. Could it be as simple as somehow re-installing the System.Web v4.0 into the GAC?

Answer 1

First of all no this is pretty bad to have this in the machine.config. Could cause tons of issues with apps running on previous .net versions.

Regarding the missing system.web.dll Maybe on that server there someone installed only the .NET 4 Client Profile. Client profile does not include system.web...