Maximum request length exceeded

Hi all, I just launch my website at IIS. I got feedback from user where he got his error. The weird thing happen where only got 1 user got this problem. Other users tested no error return. Anyone facing same problem before. Need advice from you all.
Exception Details: System.Web.HttpException: Maximum request length exceeded. Stack Trace: [HttpException (0x80004005): Maximum request length exceeded.] System.Web.HttpRequest.GetEntireRawContent() +12689488 System.Web.HttpRequest.GetMultipartContent() +221 System.Web.HttpRequest.FillInFormCollection() +357 System.Web.HttpRequest.EnsureForm() +110 System.Web.HttpRequest.get_HasForm() +12691875 System.Web.UI.Page.GetCollectionBasedOnMethod(Boolean dontReturnNull) +146 System.Web.UI.Page.DeterminPostBackMode() +129 System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoi ...