TBarCode .NET in an IIS 7.0 Web Farm
If you use TBarCode ASP.NET Web Control in a Web Farm you may encounter the following exception: Exception Type: System.ApplicationException Message: The requested image is no longer cached. The TBarCode ASP.NET Web Control uses the HttpContext.Cache object to store the generated barcode image. Since http requests are load balanced within a web farm it can occur that a specific Web Control receives a request for an image, which has been generated on a different application server (and therefore is not available in its local cache). To overcome this problem you could: Synchronize the HttpContext.Cache object on all servers in the web farm (distributed caches). This could be done with extra programming or additional third party software. or simply use Client Affinity in IIS 7.0 (recommended) Having client affinity enabled all requests are tagged with a cookie so that subsequent requests (from the same client) are routed to the same server in the web farm. Details see Application Reque