IE’s attachment handling on Tomcat via https


today something from a bit different discipline. Recently some users of one of java applications running in the company reported quite odd behavior. While they were trying to download any attachment / binary file generated by the application, they got the following error message as popup in Internet Explorer (versions 7 and 8):

„IE cannot download…………IE not able to open site..requested site is unavailable or cannot be found…”

After the message, the download was suspended and they couldn’t get the attachments. In all other browsers (FF, Opera, Chrome and Safari tested) the problem was not occuring. The application is running over https on Apache Tomcat 6.

First suspect was of course a bug in the application. After some research it turned out not to be the case. It seems to be a bug in Internet Explorer itself. Non-cache headers seem to prevent the browser from downloading attachments when working over a secure channel. Microsoft released a hotfix for it, but apparently only for the IE 6.

In order to workaround the issue, one can force Tomcat not to send the non-cache headers on response. The way to do that is to put the following valve in the Context.xml configuration file of the server (between <context> tags):

<Valve className="org.apache.catalina.authenticator.NonLoginAuthenticator"
disableProxyCaching="false" />

After that (server restart required), it seems to work fine, with no side effects.

Hope this helps,