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

if you are getting this error:

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


run 'aspnet_regiis -c' -> start>run>cmd>cd C:\WINDOWS\Microsoft.NET\Framework\"version" > aspnet_regiis -c