I'm using IIS express on VS 2013 WCF Web Template. Hi Tharaka, It would be a great help if you can help me. The request URL or the physical mapping to the URL (i.e., the physical file system path to the URL's content) is too long. Step 2: Check IIS Request filtering. The Web server is refusing to service the request because the request entity is too large. Launch “Internet Information Services (IIS) Manager”. The value must be between 0 and 2147483647. The ISAPI extension or module receives any additional data directly from the client. I've been on this problem for days. (1) in IIS, check IIS Request Filtering features setting for the WCF service > ensure "Maximum Allowed Content Length" is large enough (2) in IIS, increase UploadReadAheadSize value from 49152 to 52428800 … This occurs once per client request. The Web server cannot service the request because it is trying to negotiate a client certificate but the request entity is too large. Select the site that you are hosting your web application under it. It’s not about the maxRequestEntityAllowed since the default size is Unlimited, but how IIS handles the request. Modify the “uploadReadAheadSize” section to be like 20MB (the value there is in Bytes) In the Features section, double click “Configuration Editor”. Under “Section” select: system.webServer then serverRuntime. After some empirics we noticed that the problem was occurring only with files larger or equal to 42 KB. Step 3: Check "UploadReadAheadSize" in IIS. Here's my web.config: Large file upload failure for Web application calling WCF service – 413 Request entity too large Step 1: Collect and review WCF traces.