C# error in application

I implemented my site and suddenly im catching an error in the global.asax application_error which states the following:

Error Caught in Application_Error event Error in: http://www.mydomain.com/styles/data:image/gif;base64,R0lGODlhAQABAAD/ACwAAAAAAQABAAACADs= Error Message:A potentially dangerous Request.Path value was detected from the client (:).
SOURCE: System.Web FORM:  QUERYSTRING:  TARGETSITE: Void ValidateInputIfRequiredByConfig() STACKTRACE:    at
System.Web.HttpRequest.ValidateInputIfRequiredByConfig()     
at System.Web.HttpApplication.ValidateRequestExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()     at 
System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)

开发者_StackOverflow中文版I know this is the data for an image , but i cant find out how and why this is happen.

Any ideas?

Chr.

It's an illegal URL:

http://www.mydomain.com/styles/data:image/gif;base64,R0lGODlhAQABAAD/ACwAAAAAAQABAAACADs

The colon is a special character (signifiying protocol separator, port separator, or password separator)

As Hasan mentions, you can turn this validation off. But in truth, you should avoid having URLs like this that are just just completely invalid. Instead, URL-encode it (the part after "data").

It could be caused by a CSS minifier tool incorrectly altering data:image URLs: Why would CSS data-URIs be logged as 404 requests?