This error is caused by attempting a redirect after some content has already been sent to the browser. By default Alentus sets buffering=off in IIS to increase site performance.
There are three possible solutions for avoiding the error:
1. Add the code "Response.Buffer=True" at the top of the script to tell IIS to buffer its output before sending the page.
2. Rewrite the code so that no HTML is sent prior to a redirect occurring.
3. Request that Alentus Customer Service set buffering=true in IIS for the entire site - To make the request login to the Alentus Support Center, and Submit a Ticket to the Technical Support Department. Choose "Other IIS Settings" from the Change Request Type drop-down menu, and specify your request in the Message Details.
Option 1 is best as it is simple to do and does not affect other pages on the site.
Option 2 may be acceptable if the code is easy to change.
Option 3 may be a problem as it is a global site setting and all pages on the site will be buffered. This may cause a noticeable decrease in performance.
With buffering ON, a page is first built within IIS and only when it is complete is the page sent. This allows for redirects to occur in the middle of a page without error. With buffering OFF, content is immediately transferred to the browser and any subsequent redirects cannot execute as the content transfer has already started.
With buffering ON an initial delay may occur when sending contents to the browser. The total time to send a page is essentially the same with or without buffering but with buffering ON the initial delay may be noticeable. This is why we turn it OFF by default.
The first two solutions can be completed by the web designer alone. The third requires Alentus Customer Support to make the change.