Invalid Web Resource

I have website error messages emailed to me. I get a daily stream of about 2 to 10 errors that say "invalid web resource request" or "Invalid Script Resource Request". Many of these errors originate in the middle of the night when I highly doubt my users are online. I've not experienced any problem with my website that would indicate any programming errors, nor have any users complained about errors. I have Site Lock and it doesn't indicate any malware. I've seen comments elsewhere that point to a number of causes but attacks from some type of hackers seems one explanation.

Any insight into this? Thanks

 

Thanks for taking an interest in this. There are two types:

This:
Message This is an invalid webresource request.
StackTrace at System.Web.Handlers.AssemblyResourceLoader.System.Web.IHttpHandler.ProcessRequest(HttpContext context) at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)
Query String d=0fM3nqwkrjZMLPuYQlGXBQiTqPp4VNdXQGY8fXdt2FX4_xeA2jPnS4Eh1EEQmpiR5_D-9o6rSkJOFKWCdj0Wg4aSBphNCGZccPzWVOor4r81&t=635078704936682663
And this:
Message This is an invalid script resource request.
StackTrace at System.Web.Handlers.ScriptResourceHandler.Throw404() at System.Web.Handlers.ScriptResourceHandler.ProcessRequest(HttpContext context) at System.Web.Handlers.ScriptResourceHandler.System.Web.IHttpHandler.ProcessRequest(HttpContext context) at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)
Query String d=_d4FGWTyGX1qjAkCD3gJQf-z2n1XANknP0RS-suvEP0mV2dbrmrtq38wFFI5okKMiyWcJUl_ORoZ1fDttOIh4fOMQm0mNMR_MmR9vDgfHcL55I67HrX3HWawZt0uR46XWNk15w-5FpQ0afDEh3tp1Q2&t=ffffffffc9f82b39

As I mentioned, I've no indication these result from my users (Although, I suppose it's possible) nor do I find any issues with my site (again, I suppose it's possible there are some problems lurking in the background).

As I look at these messages, I notice "completed Synchronously". I do have one page, where a user can make a comment, that is coded at the top of the .aspx page with:
<%@PageAsync="true"Title...........

and then in the VB code behind page:
Imports System.Net.Mail
Imports System.Threading

And then in my routine for sending me a mail message when a use puts in a comment:
mySmtpClient.SendAsync(mymessage, state)

I did this because the user response after putting in a comment seemed to be slowed down by the routine for sending me an email. Although, honestly, it didn't seem to help a lot. Also, I've never seen a correlation between the comments I personally post and these error messages. Again, lots of these errors pop up at something 3:00 am - hard to believe my users are posting comments at that time. Actually, my site gets a very low volume of comments even in the summer when it's most used. Now, at this time of the year, there is very little traffic.

However, if you think I should remove the async code, I will. Thanks.

 

Thank you very much for the great info - I'll implement these steps and post back in a few days. Thanks again!

 

Just an FYI on progress: enabled raw logs and downloaded IIS Manager - all went smoothly. Now starting the 48 hour wait.