Unable to find script library '/aspnet_client/ system_web/1_1_4322/WebUIValidation.js'

If you get this error using .NET 1.1, try reinstalling the JavaScript file by navigating to your Framework directory (eg. C:\WINDOWS\Microsoft.NET\Framework\v1.1.4322) and running the following command:

aspnet_regiis -c

Create a virtual directory under your web site root called ‘aspnet_client’ with all the default options and point it to the aspnet_client folder under the web root (eg. C:\Inetpub\wwwroot\aspnet_client).

Make sure you have appropriate backups before attempting these suggestions, in case you need to roll back.