There is a separate web.config file for each Web Application / IIS Website which is running an instance of SharePoint. For example, if Sharepoint, Central Admin and the MySite host are all running as separate Web applications (different Application pools) on separate IIS sites, there will be a web.config file in the root of the virtual directory for each application. There is also a separate web.config file which contains configuration details for the “_layouts”, “_catalogs”, etc directories of SharePoint sites.
You should not make changes to the web.config file in a production environment, or while in production. Back up your entire SharePoint environment, including all databases prior to commencing any major troubleshooting or configuration changes. You should attempt and test any modifications to the web.config file in a non-production environment which is configured the same as the live environment. Once you are confident the the changes apply the necessary changes if required to the live environment while it is not in use. The IIS Website will automatically reset when the web.config file is saved so changes will be applied immediately. Be sure that you have not left syntax or any other errors in the file before saving changes.
The web.config files are genearally found in the following locations:
- web.config file in the root folder of each virtual server / IIS Application.
This is the usually the file that contains most of the web configuration of a SharePoint site collection. To display full errors you would need to modify this web.config file. There may be one for each of the SharePoint applications running in some cases (MySites, Multiple Portals or Instances of SharePoint, Central Admin, etc.). If this is the case, you will only need to modify the web.config file which is in the root of the virtual directory for the instance of SharePoint which you using. To find out which directory is used by various SharePoint applications/websites, view the properties of the SharePoint website in IIS and from the “Home Directory” tab, the value in the “Local path” field will take you to the directory where the web.config file is for the specific instance of SharePoint / Application in IIS.
- web.config file used in Web Part resources for the Global Assembly Cache (GAC)
- web.config configuration file(s) for extending other virtual servers
- web.config file which defines configuration settings for the /_vti_bin virtual directory
- web.config file which defines configuration settings for the /_layouts virtual directory
- web.config configuration file for Central Administration pages.