Error message when an ASP.NET application tries to create a new application domain: "Can not access file 'System.Web' because it is being used by another process"

Consider the following scenario. You create a Microsoft ASP.NET application. The application tries to create a new application domain. In this scenario, you may receive the following configuration error message in the Web browser:Notes

• In this error message, the words "can not" are a misspelling for the word "cannot."
• This problem is more likely to occur when the Web server is under a heavy load.

This problem occurs when a process modifies the Machine.config file at the same time that the System.web.dll file tries to access the Machine.config file. This causes a file sharing violation.

Note The error message that is mentioned in the "Symptoms" section indicates that the System.web.dll file cannot be accessed. However, the problem is that the Machine.config file cannot be accessed by the System.web.dll file.

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.